Abstract: Objective To further improve the operational efficiency and economic benefits of high-speed railways and to achieve lightweight carbody design, it is necessary to carry out topology optimization of the inner-end wall structure of EMU（electric multiple unit） carbodies. Method Focusing on the inner-end wall of EMU carbody, under two analysis conditions-structural modal and air-tightness strength, and taking the structure′s natural mode and stress as constraints, a finite element model for topology optimization is established with minimizing structural mass as the objective function. A topology optimization analysis of the inner-end wall structure is performed using the variable density method to determine its load force flow transmission path. To verify the reliability of the topology optimization results, a new structural layout for the load-bearing components is designed based on an optimized configuration while retaining the original carbody framework. A finite element model is built to compare the effects of the original and optimized inner-end wall structures on both the overall vehicle and the localized structural performance. Result ＆ Conclusion The optimized structure achieves a 30% reduction in inner-end wall mass without compromising overall vehicle performance, thereby confirming the feasibility of the topology-optimized structure.