Abstract: Based on Bentley PowerCivil, this article adopted the idea of tunnel design, referred to the information of ground model, geology and line model, and implemented the precise establishment of tunnel design model according to surrounding rock conditions, completed the automatic addition of engineering information with IFC/IFD coding standard. By sorting out the differences of model structure tree between design stage and construction stage, the automatic transformation from geometric decomposition and design stage information to construction stage was implemented. A complete set of auxiliary design system and process for railway tunnel design and construction based on BIM technology was built. Practice has proved that the system can effectively assist tunnel design and improve design accuracy by combining the geological information and design parameters. It was solved the problem of continuous application of the model in the whole life cycle of the project through information connection and phase model transformation.