How to make full use of the multi-source heterogeneous information of complex geology and engineering structure in the process of metro foundation pit construction to realize the construction digital fabrication is a difficult problem in metro engineering construction. In this paper

an idea of building information modeling (BIM) customization is proposed to solve this problem by effectively integrating engineering structure model and geological model

and establishing the foundation pit construction simulation method of dynamic coupling between earthwork excavation and retaining structure construction. Using industry foundation classes (IFC) standard

the geological body and engineering structure are extended and defined respectively

and the data system of foundation pit engineering based on IFC standard is constructed. Based on the Autodesk software platform

the foundation pit structure component library and parametric component modeling technology are developed to create a plug-in foundation pit structure modeling module. The three-dimensional (3D) geological modeling method based on borehole data is established

and a dynamic cutting method of geological model for the construction process simulation is established. The geological model is divided into 3D blocks at different excavation stages

and the 3D multi-phase geological model is formed. On this basis

the topology is reconstructed and the geological body and retaining structure are integrated; the multi-stage excavation BIM model is thus constructed. By dynamically loading construction schedule and time information on the integrated multi-stage model

the construction simulation method of metro foundation pit engineering based on BIM technology is then developed. Finally

the feasibility and effectiveness of the proposed simulation method are demonstrated through an engineering example.