Railway marshalling yards are the core of train disassembly and reassembly, and the quality of their network coverage directly affects the efficiency of railway transportation. Traditional network optimization solutions are insufficient in dealing with special scenarios such as base station interference and sensitive electromagnetic environments in marshalling yards. A wireless environment digital twin platform based on ray tracing technology is introduced, along with its system architecture, optimization process, and result visualization. Taking a marshalling yard along the Daqin Railway as a case study, the platform simulates and optimizes the issue of weak signal coverage. The simulation results show that compared with the initial base station deployment plan, the optimized base station parameters have effectively improved the overall signal reception quality. This not only supports the design work but also provides theoretical support and technical accumulation for the high-quality construction and optimization of the next-generation railway mobile communication system 5G for Railway(5G-R) dedicated network for railway marshalling yards based on 5G technology.