Abstract: Temperature and residual stress field of 201 stainless steel spot welding process were simulated by Ansys finite element software.The characteristics of spot heating and cooling and the temperature distribution were analyzed,and the diversification and distribution of stress were discussed.The results show that with spot welding heating,symmetrical ellipse nugget gradually forms along the joint surface,and compressive stress is mainly in the nugget;at cooling moment,the isotherm of welding area reduces with the shape of ellipse,and the stress in nugget transforms to tensile stress.The actual nugget sizes of spot welding joints are measured to verify that the simulation results are accurate and reliable.