Abstract: Faced with the management challenges brought by the expanding scale and increasing complexity of railway project construction, this paper proposed a construction method of digital twin scenarios for railway smart construction sites based on Building Information Modeling (BIM) and multi-source data fusion. The paper integrated multi-source data including BIM, geographic information system, and Internet of Things sensors to construct a digital twin framework supporting the full life cycle of railway engineering, and realized intensive management and intelligent response of construction site information. It investigated the collection and fusion strategies as well as unified standards of multi-source data, and put forward the technical path for digital twin scenario construction. Laboratory tests on physical tunnel sections and on-site pilot verifications show that the proposed method effectively improves project management efficiency and reduces operation and maintenance costs, with geometric-semantic error within 2 cm and response delay within 1.8 s. This study provides technical support and a feasible solution for the application of digital twin technology in smart construction sites of railway and similar linear engineering projects.