The BIM modeling of Multi-Component Subgrade in a Railway Station (MCSRS) suffers from an inefficient manual approach due to its specific features and absence of a data standard. The Industry Foundation Classes (IFC) has been widely used for describing various components in the building industry while its current version fails to depict an MCSRS. In this study, the IFC is extended to describe the geometric information and hierarchy for an MCSRS, based on which an automatic workflow for converting the original design data to the corresponding 3D BIM model complying with IFC standard is developed. To validate the methodology, a real-world case is used for testing the modeling result, in which several different modeling cases between two cross-sections are examined. The results show that the BIM modeling for an MCSRS is greatly accelerated compared with the manual modeling approach and can be used as a cross-platform tool.