Hydrodynamic flow field calculation is an important content in the research of hydraulic engineering and waterway regulation engineering.To realize independent research and development of flow field visualization and facilitate editing，a method of flow field generation and visualization based on CAD secondary development is proposed.Using the hybrid programming technology of Fortran and C#，based on dynamic link library，the secondary development of AutoCAD is carried out through the transfer of C# and Fortran parameters.This method can draw the flow field vector map and flow field cloud map quickly on AutoCAD platform，and can also represent the size of the value with different colors，so as to realize the visual editing of the flow field.The method is demonstrated and applied in Changshou River section of the Three Gorges Reservoir area，and the results show that it has a better visualization effect and practical value.