Abstract: Aiming at the construction stage of railway construction, this article studied the construction process of digital filling of railway subgrade based on BIM technology.By installing gradient control system in bulldozers and graders, it was implemented the precise control of geometric dimension of roadbed filling layer. By installing continuous compaction system in roller, it was ensured the compaction quality of roadbed filling layer. Engineering application indicate that the visual control of geometric size and compaction quality of subgrade filling layer is implemented and the slope and thickness of each compaction layer are controlled steadily under the application of railway subgrade digital filling construction. The control speed and precision of filling layer geometry dimension are obviously improved, compaction quality is obviously improved, and the surface transverse and longitudinal slopes meet the design requirements. The digital railway subgrade filling construction has carried out strict process and quality control, and the construction data are stored, analyzed and displayed digitally, which achieves the goal of stabilizing the construction quality and traceability of the process.