diff --git a/freecad/main.md b/freecad/main.md
new file mode 100644
index 0000000..7d14d82
--- /dev/null
+++ b/freecad/main.md
@@ -0,0 +1,211 @@
+# freecad 二次开发文档
+
+
+
+## freecad 源代码目录结构
+
+**src/：**此目录包含 FreeCAD 的核心源代码。
+
+**src/App：**包含 FreeCAD 的应用程序对象的实现，如文档、事务管理和撤销/重做系统。
+
+**src/Base：**包含一些基本类和函数，如向量、矩阵和几何实体。
+
+**src/Main：**包含 FreeCAD 的主程序入口点。
+
+**src/Mod：**包含 FreeCAD 的各个模块和工作台的实现，如 Part、Sketcher、FEM 等。
+
+**src/Gui：**包含 FreeCAD 的图形用户界面（GUI）的实现，使用 Qt 框架构建。
+
+**src/Tools：**包含一些实用工具，如编译和构建脚本。
+
+**data/**：此目录包含 FreeCAD 的一些资源文件，如图标、模板、样式表等。
+
+**doc/：**此目录包含 FreeCAD 的开发文档，包括编码规范、开发指南等。
+
+**ext/：**此目录包含 FreeCAD 依赖的外部库，如 Open CASCADE、Eigen 等
+
+
+
+## fem步骤
+
+
+
+1. 创建或导入一个几何模型。
+2. 转到 FEM 工作台。
+3. 创建一个分析对象（Analysis Container）。
+4. 定义材料属性。
+5. 为模型添加约束，例如固定、力和压力。
+6. 创建一个网格，将几何体划分为有限元。
+7. 选择求解器，如 CalculiX、Elmer 或 Z88。
+8. 运行分析。
+9. 查看和分析结果。
+
+
+
+
+## python 自动创建fem分析脚本
+
+```python
+#! /usr/bin/env python3
+# -*- coding: utf-8 -*-
+# vim:fenc=utf-8
+#
+# Copyright © 2023 veypi <i@veypi.com>
+#
+# Distributed under terms of the Apache license.
+"""
+
+"""
+
+doc = App.newDocument("Scripted_CalculiX_Cantilever3D")
+import Part
+
+box_obj = doc.addObject('Part::Box', 'Box')
+box_obj.Height = box_obj.Width = 1000
+box_obj.Length = 8000
+
+# see how our part looks like
+import FreeCADGui
+
+FreeCADGui.ActiveDocument.activeView().viewAxonometric()
+FreeCADGui.SendMsgToActiveView("ViewFit")
+
+import ObjectsFem
+
+# analysis
+analysis_object = ObjectsFem.makeAnalysis(doc, "Analysis")
+
+# solver (we gone use the well tested CcxTools solver object)
+solver_object = ObjectsFem.makeSolverCalculixCcxTools(doc, "CalculiX")
+solver_object.GeometricalNonlinearity = 'linear'
+solver_object.ThermoMechSteadyState = True
+solver_object.MatrixSolverType = 'default'
+solver_object.IterationsControlParameterTimeUse = False
+analysis_object.addObject(solver_object)
+
+# material
+material_object = ObjectsFem.makeMaterialSolid(doc, "SolidMaterial")
+mat = material_object.Material
+mat['Name'] = "Steel-Generic"
+mat['YoungsModulus'] = "210000 MPa"
+mat['PoissonRatio'] = "0.30"
+mat['Density'] = "7900 kg/m^3"
+material_object.Material = mat
+analysis_object.addObject(material_object)
+
+# fixed_constraint
+fixed_constraint = ObjectsFem.makeConstraintFixed(doc, "FemConstraintFixed")
+fixed_constraint.References = [(doc.Box, "Face1")]
+analysis_object.addObject(fixed_constraint)
+
+# force_constraint
+force_constraint = ObjectsFem.makeConstraintForce(doc, "FemConstraintForce")
+force_constraint.References = [(doc.Box, "Face2")]
+force_constraint.Force = 9000000.0
+force_constraint.Direction = (doc.Box, ["Edge5"])
+force_constraint.Reversed = True
+analysis_object.addObject(force_constraint)
+
+## fem mesh
+
+femmesh_obj = ObjectsFem.makeMeshGmsh(doc, box_obj.Name + "_Mesh")
+femmesh_obj.Part = doc.Box
+
+doc.recompute()
+
+from femmesh.gmshtools import GmshTools as gt
+
+gmsh_mesh = gt(femmesh_obj)
+error = gmsh_mesh.create_mesh()
+print(error)
+
+analysis_object.addObject(femmesh_obj)
+
+doc.recompute()
+
+# activating analysis
+
+import FemGui
+
+FemGui.setActiveAnalysis(doc.Analysis)
+
+#from femtools import ccxtools
+#fea = ccxtools.FemToolsCcx()
+#fea.purge_results()
+#fea.run()
+
+from femtools import ccxtools
+
+fea = ccxtools.FemToolsCcx()
+fea.update_objects()
+fea.setup_working_dir()
+fea.setup_ccx()
+message = fea.check_prerequisites()
+if not message:
+    fea.purge_results()
+    fea.write_inp_file()
+    # on error at inp file writing, the inp file path "" was returned (even if the file was written)
+    # if we would write the inp file anyway, we need to again set it manually
+    # fea.inp_file_name = '/tmp/FEMWB/FEMMeshGmsh.inp'
+    fea.ccx_run()
+    fea.load_results()
+else:
+    FreeCAD.Console.PrintError(
+        "Houston, we have a problem! {}\n".format(message))  # in report view
+    print("Houston, we have a problem! {}\n".format(
+        message))  # in Python console
+
+###
+
+# show resutlt
+for m in analysis_object.Group:
+    if m.isDerivedFrom('Fem::FemResultObject'):
+        result_object = m
+        break
+
+femmesh_obj.ViewObject.setNodeDisplacementByVectors(
+    result_object.NodeNumbers, result_object.DisplacementVectors)
+print(result_object.DisplacementVectors[-1])
+import time
+
+femmesh_obj.ViewObject.applyDisplacement(20)
+import requests
+
+d = requests.get(url="http://192.168.5.172:8015/file/123")
+print("|%s|" % (d.text.strip()))
+# 每秒请求服务器渲染变形程度
+n = 0
+data = 0
+while 1:
+    time.sleep(0.01)
+    d = requests.get(url="http://192.168.5.172:8015/file/123")
+    data = int(d.text.strip())
+    # 更新ui
+    FreeCAD.Gui.updateGui()
+    #print("%s/%s"%(n, data))
+    femmesh_obj.ViewObject.applyDisplacement(n)
+    if data > n:
+        n = n + 1
+    if data < n:
+        n = n - 1
+
+```
+
+
+## 添加有限元fem 求解器
+
+[参考源码](https://github.com/FreeCAD/FreeCAD/compare/a03eb6b9625ba...dfc01ec949525)
+
+步骤：
+    
+
+[添加mesh导出程序](https://github.com/FreeCAD/FreeCAD/commit/e100971fa0a0c17b5e4906ac540fa31ac0d11766)
+
+[添加求解器，写入程序，任务程序，约束程序](https://github.com/FreeCAD/FreeCAD/commit/cdcd271b4c97a27431dc28d852f6ed7e171dba67)
+
+[添加求解器单元测试](https://github.com/FreeCAD/FreeCAD/commit/005c66f4ecc7fb1690a54592a00ec490146b985d)
+
+[添加文档](https://github.com/FreeCAD/FreeCAD/commit/cfc08b811ff09628b1468e21e9e823587efc799a)
+
+[添加界面参数](https://github.com/FreeCAD/FreeCAD/commit/dfc01ec949525162c70648ea6d6d93c818907f1f)
+