<p>The application of BIM (Building Information Modeling) technology in tunnel engineering is limited by the complexity of tunnel structure model construction and the integration difficulties with the geological model. In this study, a tunnel model integration method based on BIM technology was proposed in the context of the Loushan Tunnel Project. Firstly, geological borehole data and stratigraphic sequence optimization logic were used to determine the stratigraphic sequence. Then Revit software was used to construct a high-precision geological BIM model. Secondly, the structural component model was parametrically designed, and the tunnel structure BIM model was generated by writing an adaptive placement and splicing program through the built-in plug-in Dynamo. Finally, Dynamo coordinate matching function was developed for automatically aligning the position of the tunnel structure model in the geological model, thus realizing the seamless integration of the two. The integrated approach not only bypassed the data compatibility problem between BIM and geological modeling software, but also significantly improved the accuracy of constructing the geological model in BIM software. And the modeling process of the tunnel structure BIM model was optimized and simplified. In addition, the application of BIM technology in the field of tunneling engineering was further promoted.</p>