Abstract: In this paper，TRIZ theory is used as an innovative tool to analyze the problems of stainless steel car-body welding deformation in rail transit industry，the principle and method of TRIZ are applied to solve the problems. Through functional analysis and causal analysis methods，the causes of welding deformation are analyzed in detail. Starting from the excess heat and heat transfer in the welding process，four root causes are detected.The technical contradiction，physical contradiction，material field model，effect theory and other tools in TRIZ theory are used to solve these problems respectively，and the solution scheme is verified by field tests. Finally，the comprehensive ideal solution is obtained as the implementation control scheme.