diff --git a/libopenfpga/libopenfpgautil/src/openfpga_digest.cpp b/libopenfpga/libopenfpgautil/src/openfpga_digest.cpp
index 3ae2083df..00cbbe1e3 100644
--- a/libopenfpga/libopenfpgautil/src/openfpga_digest.cpp
+++ b/libopenfpga/libopenfpgautil/src/openfpga_digest.cpp
@@ -235,4 +235,20 @@ void create_directory(const std::string& dir_path, const bool& recursive) {
   }
 }
 
+/******************************************************************** 
+ * Write a number of space to a file 
+ ********************************************************************/
+bool write_space_to_file(std::fstream& fp,
+                         const size_t& num_space) {
+  if (false == valid_file_stream(fp)) {
+    return false;
+  }
+
+  for (size_t i = 0; i < num_space; ++i) {
+    fp << " ";
+  }
+
+  return true;
+}
+
 } /* namespace openfpga ends */
diff --git a/libopenfpga/libopenfpgautil/src/openfpga_digest.h b/libopenfpga/libopenfpgautil/src/openfpga_digest.h
index 0e1cd5d76..a28b2c4d0 100644
--- a/libopenfpga/libopenfpgautil/src/openfpga_digest.h
+++ b/libopenfpga/libopenfpgautil/src/openfpga_digest.h
@@ -25,6 +25,9 @@ std::string find_path_dir_name(const std::string& file_name);
 
 void create_directory(const std::string& dir_path, const bool& recursive = true); 
 
+bool write_space_to_file(std::fstream& fp,
+                         const size_t& num_space);
+
 } /* namespace openfpga ends */
 
 #endif
diff --git a/openfpga/src/base/openfpga_build_fabric.cpp b/openfpga/src/base/openfpga_build_fabric.cpp
index 67203216a..e013ab267 100644
--- a/openfpga/src/base/openfpga_build_fabric.cpp
+++ b/openfpga/src/base/openfpga_build_fabric.cpp
@@ -11,6 +11,7 @@
 #include "device_rr_gsb.h"
 #include "device_rr_gsb_utils.h"
 #include "build_device_module.h"
+#include "fabric_hierarchy_writer.h"
 #include "openfpga_build_fabric.h"
 
 /* Include global variables of VPR */
@@ -85,4 +86,28 @@ int build_fabric(OpenfpgaContext& openfpga_ctx,
   return CMD_EXEC_SUCCESS;
 } 
 
+/********************************************************************
+ * Build the module graph for FPGA device
+ *******************************************************************/
+int write_fabric_hierarchy(const OpenfpgaContext& openfpga_ctx,
+                           const Command& cmd, const CommandContext& cmd_context) { 
+
+  CommandOptionId opt_verbose = cmd.option("verbose");
+
+  /* Check the option '--file' is enabled or not 
+   * Actually, it must be enabled as the shell interface will check 
+   * before reaching this fuction
+   */
+  CommandOptionId opt_file = cmd.option("file");
+  VTR_ASSERT(true == cmd_context.option_enable(cmd, opt_file));
+  VTR_ASSERT(false == cmd_context.option_value(cmd, opt_file).empty());
+
+  std::string hie_file_name = cmd_context.option_value(cmd, opt_file);
+
+  /* Write hierarchy to a file */
+  return write_fabric_hierarchy_to_text_file(openfpga_ctx.module_graph(),
+                                             hie_file_name,
+                                             cmd_context.option_enable(cmd, opt_verbose));
+}
+
 } /* end namespace openfpga */
diff --git a/openfpga/src/base/openfpga_build_fabric.h b/openfpga/src/base/openfpga_build_fabric.h
index 3b63c7ab2..6a090397d 100644
--- a/openfpga/src/base/openfpga_build_fabric.h
+++ b/openfpga/src/base/openfpga_build_fabric.h
@@ -18,6 +18,9 @@ namespace openfpga {
 int build_fabric(OpenfpgaContext& openfpga_ctx,
                  const Command& cmd, const CommandContext& cmd_context); 
 
+int write_fabric_hierarchy(const OpenfpgaContext& openfpga_ctx,
+                           const Command& cmd, const CommandContext& cmd_context); 
+
 } /* end namespace openfpga */
 
 #endif
diff --git a/openfpga/src/base/openfpga_setup_command.cpp b/openfpga/src/base/openfpga_setup_command.cpp
index 8f4b0cec3..2a3b11227 100644
--- a/openfpga/src/base/openfpga_setup_command.cpp
+++ b/openfpga/src/base/openfpga_setup_command.cpp
@@ -238,6 +238,37 @@ ShellCommandId add_openfpga_build_fabric_command(openfpga::Shell<OpenfpgaContext
   return shell_cmd_id;
 }
 
+/********************************************************************
+ * - Add a command to Shell environment: write_fabric_hierarchy
+ * - Add associated options 
+ * - Add command dependency
+ *******************************************************************/
+static 
+ShellCommandId add_openfpga_write_fabric_hierarchy_command(openfpga::Shell<OpenfpgaContext>& shell,
+                                                           const ShellCommandClassId& cmd_class_id,
+                                                           const std::vector<ShellCommandId>& dependent_cmds) {
+
+  Command shell_cmd("write_fabric_hierarchy");
+
+  /* Add an option '--file' */
+  CommandOptionId opt_file = shell_cmd.add_option("file", true, "Specify the file name to write the hierarchy to");
+  shell_cmd.set_option_short_name(opt_file, "f");
+  shell_cmd.set_option_require_value(opt_file, openfpga::OPT_STRING);
+
+  /* Add an option '--verbose' */
+  shell_cmd.add_option("verbose", false, "Show verbose outputs");
+
+  /* Add command 'write_fabric_hierarchy' to the Shell */
+  ShellCommandId shell_cmd_id = shell.add_command(shell_cmd, "Write the hierarchy of FPGA fabric graph to a plain-text file");
+  shell.set_command_class(shell_cmd_id, cmd_class_id);
+  shell.set_command_const_execute_function(shell_cmd_id, write_fabric_hierarchy);
+
+  /* Add command dependency to the Shell */
+  shell.set_command_dependency(shell_cmd_id, dependent_cmds);
+
+  return shell_cmd_id;
+}
+
 void add_openfpga_setup_commands(openfpga::Shell<OpenfpgaContext>& shell) {
   /* Get the unique id of 'vpr' command which is to be used in creating the dependency graph */
   const ShellCommandId& vpr_cmd_id = shell.command(std::string("vpr"));
@@ -317,9 +348,19 @@ void add_openfpga_setup_commands(openfpga::Shell<OpenfpgaContext>& shell) {
   /* The 'build_fabric' command should NOT be executed before 'link_openfpga_arch' */
   std::vector<ShellCommandId> build_fabric_dependent_cmds;
   build_fabric_dependent_cmds.push_back(link_arch_cmd_id);
-  add_openfpga_build_fabric_command(shell,
-                                    openfpga_setup_cmd_class,
-                                    build_fabric_dependent_cmds);
+  ShellCommandId build_fabric_cmd_id = add_openfpga_build_fabric_command(shell,
+                                                                         openfpga_setup_cmd_class,
+                                                                         build_fabric_dependent_cmds);
+
+  /******************************** 
+   * Command 'write_fabric_hierarchy' 
+   */
+  /* The 'write_fabric_hierarchy' command should NOT be executed before 'build_fabric' */
+  std::vector<ShellCommandId> write_fabric_hie_dependent_cmds;
+  write_fabric_hie_dependent_cmds.push_back(build_fabric_cmd_id);
+  add_openfpga_write_fabric_hierarchy_command(shell,
+                                              openfpga_setup_cmd_class,
+                                              write_fabric_hie_dependent_cmds);
 } 
 
 } /* end namespace openfpga */
diff --git a/openfpga/src/fabric/fabric_hierarchy_writer.cpp b/openfpga/src/fabric/fabric_hierarchy_writer.cpp
new file mode 100644
index 000000000..7b752f015
--- /dev/null
+++ b/openfpga/src/fabric/fabric_hierarchy_writer.cpp
@@ -0,0 +1,129 @@
+/***************************************************************************************
+ * Output internal structure of Module Graph hierarchy to file formats
+ ***************************************************************************************/
+/* Headers from vtrutil library */
+#include "vtr_log.h"
+#include "vtr_assert.h"
+#include "vtr_time.h"
+
+/* Headers from openfpgautil library */
+#include "openfpga_digest.h"
+
+#include "openfpga_naming.h"
+
+#include "fabric_hierarchy_writer.h"
+
+/* begin namespace openfpga */
+namespace openfpga {
+
+/***************************************************************************************
+ * Recursively output child module of the parent_module to a text file
+ * We use Depth-First Search (DFS) here so that we can output a tree down to leaf first
+ * Add space (indent) based on the depth in hierarchy
+ * e.g. depth = 1 means a space as indent
+ ***************************************************************************************/
+static 
+int rec_output_module_hierarchy_to_text_file(std::fstream& fp,
+                                             const size_t& hie_depth,
+                                             const ModuleManager& module_manager,  
+                                             const ModuleId& parent_module,
+                                             const bool& verbose) {
+  if (false == valid_file_stream(fp)) {
+    return 2;
+  }
+
+  /* Iterate over all the child module */
+  for (const ModuleId& child_module : module_manager.child_modules(parent_module)) {
+    if (false == write_space_to_file(fp, hie_depth)) {
+      return 2;
+    }
+
+    if (true != module_manager.valid_module_id(child_module)) {
+      VTR_LOGV_ERROR(verbose,
+                     "Unable to find the child module '%u'!\n",
+                     size_t(child_module));
+      return 1;
+    }
+
+    fp << module_manager.module_name(child_module);
+    fp << "\n";
+
+    /* Go to next level */
+    int status = rec_output_module_hierarchy_to_text_file(fp,
+                                                          hie_depth + 1, /* Increment the depth for the next level */
+                                                          module_manager,
+                                                          child_module,
+                                                          verbose);
+    if (0 != status) {
+      return status;
+    }
+  }
+
+  return 0;
+}
+
+/***************************************************************************************
+ * Write the hierarchy of modules to a plain text file
+ * e.g.,
+ *    <module_name>
+ *      <child_module_name>
+ *        ...
+ * This file is mainly used by hierarchical P&R flow 
+ *
+ * Return 0 if successful
+ * Return 1 if there are more serious bugs in the architecture 
+ * Return 2 if fail when creating files
+ ***************************************************************************************/
+int write_fabric_hierarchy_to_text_file(const ModuleManager& module_manager,
+                                        const std::string& fname,
+                                        const bool& verbose) {
+  std::string timer_message = std::string("Write fabric hierarchy to plain-text file '") + fname + std::string("'");
+
+  std::string dir_path = format_dir_path(find_path_dir_name(fname));
+
+  /* Create directories */
+  create_directory(dir_path);
+
+  /* Start time count */
+  vtr::ScopedStartFinishTimer timer(timer_message);
+
+  /* Use default name if user does not provide one */
+  VTR_ASSERT(true != fname.empty());
+
+  /* Create a file handler*/
+  std::fstream fp;
+  /* Open a file */
+  fp.open(fname, std::fstream::out | std::fstream::trunc);
+
+  /* Validate the file stream */
+  check_file_stream(fname.c_str(), fp);
+
+  /* Find top-level module */
+  std::string top_module_name = generate_fpga_top_module_name();
+  ModuleId top_module = module_manager.find_module(top_module_name);
+  if (true != module_manager.valid_module_id(top_module)) {
+    VTR_LOGV_ERROR(verbose,
+                   "Unable to find the top-level module '%s'!\n",
+                   top_module_name.c_str());
+    return 1;
+  }
+  
+  /* Record current depth of module: top module is the root with 0 depth */
+  size_t hie_depth = 0;
+
+  fp << top_module_name << "\n";
+
+  /* Visit child module recursively and output the hierarchy */
+  int err_code = rec_output_module_hierarchy_to_text_file(fp,
+                                                          hie_depth + 1, /* Start with level 1 */
+                                                          module_manager,  
+                                                          top_module,
+                                                          verbose);
+
+  /* close a file */
+  fp.close();
+
+  return err_code;
+}
+
+} /* end namespace openfpga */
diff --git a/openfpga/src/fabric/fabric_hierarchy_writer.h b/openfpga/src/fabric/fabric_hierarchy_writer.h
new file mode 100644
index 000000000..48e112c76
--- /dev/null
+++ b/openfpga/src/fabric/fabric_hierarchy_writer.h
@@ -0,0 +1,23 @@
+#ifndef FABRIC_HIERARCHY_WRITER_H
+#define FABRIC_HIERARCHY_WRITER_H
+
+/********************************************************************
+ * Include header files that are required by function declaration
+ *******************************************************************/
+#include "vpr_context.h"
+#include "openfpga_context.h"
+
+/********************************************************************
+ * Function declaration
+ *******************************************************************/
+
+/* begin namespace openfpga */
+namespace openfpga {
+
+int write_fabric_hierarchy_to_text_file(const ModuleManager& module_manager,
+                                        const std::string& fname,
+                                        const bool& verbose);
+
+} /* end namespace openfpga */
+
+#endif
diff --git a/openfpga/test_script/and_k6_frac.openfpga b/openfpga/test_script/and_k6_frac.openfpga
index 20a75a661..014142fb1 100644
--- a/openfpga/test_script/and_k6_frac.openfpga
+++ b/openfpga/test_script/and_k6_frac.openfpga
@@ -24,6 +24,8 @@ lut_truth_table_fixup #--verbose
 #  - Enable pin duplication on grid modules 
 build_fabric --compress_routing --duplicate_grid_pin #--verbose
 
+write_fabric_hierarchy --file ./fabric_hierarchy.txt
+
 # Repack the netlist to physical pbs
 # This must be done before bitstream generator and testbench generation
 # Strongly recommend it is done after all the fix-up have been applied