Thermal elastic-plastic finite element method was used to conduct numerical simulation for the hybrid welding test of 304 stainless steel based on Ansys Workbench software platform. The residual stress and deformation results obtained by numerical calculation were in good agreement with the welding test results. The changes of temperature field and structure field under different laser power are analyzed and the results show that the laser power has an effect on the maximum deformation and the peak value of residual stress. The larger the laser power is, the more the maximum deformation and the peak residual stress of 304 stainless steel are. Because the energy input of laser welding is concentrated, the influence of laser power on thermal deformation and residual stress distribution is not obvious.