Abstract: This article focuses on the welding deformation control requirements in the manufacturing process of stainless steel car bodies. It selects 12 common types of thin-plate welding joints in the structure of railway vehicle bodies as the research objects, covering different types such as butt joints, lap joints, and corner joints. Through precise measurement and statistical analysis, the distribution characteristics of transverse shrinkage and longitudinal shrinkage rate data for different joint types are obtained. Based on the experimental results, the study clarifies that the transverse shrinkage of butt joints is concentrated in the range of 0.50~0.60mm, and the longitudinal shrinkage rate of double-sided welds is significantly higher than that of single-sided welds. Based on this, specific process allowance recommendations are proposed: a compensation of 0.5mm per transverse weld and a 2~3mm per meter allowance for longitudinal welds. These verified reference data provide an important basis for the process design of stainless steel car bodies, which can be directly applied to production practice, effectively controlling product dimensional accuracy, reducing the workload of repair and assembly during the process, and significantly improving production efficiency while ensuring product quality. This has a positive impact on the optimization of manufacturing processes for rail transit equipment.