Abstract: Aiming at the batch 3D modeling of railway culvert portal under various constraints such as aperture and angle, this paper took the general diagram of railway reinforced concrete frame box as the research object, and studied on the CATIA secondary development with Excel as data source. Using VB.NET to call CATIA class library, using independent form display and loading data of general diagram, the paper developed 3D automatic modeling program of culvert portal based on VB Script. The 3D portal models in CATIA could be automatically created, stretched, and cut. The model files were output in batches. The program was applied in the railway BIM design project. The application effect was good. The program changed the manual modeling work mode, improved the efficiency of modeling.