Jingtianlutu is the first BIM software for highway engineering in domestic transportation industry. Addressing the issue of the software's inability to quickly analyze the bearing capacity of multi-layered geological bodies, an interface program between Jingtianlutu and the common bearing capacity analysis software FLAC^3D was developed using the C# language on the Visual Studio 2019 platform, based on the 3D WinForms control Eyeshot. The interface program has a graphical display interface, which can read the terrain data of multi-layered geological bodies from the Jingtianlutu, and layer the geological bodies according to the geological survey data, and obtain the geometry data and material properties of each stratum. The finite element mesh model is automatically created in ANSYS using the APDL command flow. Utilizing the FLAC^3D command flow, the pre-processing tasks such as reading and converting mesh models, defining material properties and boundary conditions are automatically completed before the solution process begins. Commonly used analysis results are then automatically exported and sent back to Jingtianlutu. This study provides detailed information on the research and implementation ideas, development tools, development processes, and key algorithms of the interface program. An example is used to verify the interface program, demonstrating that the analysis results of the bearing capacity of multi-layered geological bodies using the interface program are consistent with the results obtained through direct use of ANSYS modeling and FLAC^3D calculation. However, the former takes approximately 2 minutes, while the latter takes around 0.6 hours, which significantly enhances the efficiency of designers.