Abstract: In order to quickly and accurately generate the skeleton line needed for BIM modeling of railway tunnel, and add necessary design information to the skeleton line, this paper wrote programs through secondary development, used C++ language and CAA development function provided by Dassault platform to create skeleton line as a custom feature, read the design data through the program, generated the skeleton line in batch.The skeleton line generated by this program is faster than before and contains more design information, has the function of automatically updating with the modification of input data.The application in a tunnel shows that the software can improve the efficiency of skeleton line modeling and greatly reduce the work load of designers in the process of modeling and modification.