Abstract: The three-dimensional finite element model of 304 stainless steel T-joint was established to study the influence of welding sequence on thermal deformation and residual stress of T-joint during laser-arc hybrid welding. A composite heat source model combining Gaussian surface heat source and 3D Gaussian body heat source was used to simulate the laser and arc hybrid heat sources. The reliability of numerical simulation was verified by laser-arc hybrid build up welding test of 304 stainless steel. Numerical simulation results of weld section pool morphology are in good agreement with the actual welding experimental results, which indicates that the established heat source model can effectively simulate the coupling effect of laser-arc hybrid heat sources. The temperature field, residual stress and thermal deformation of 304 stainless steel T-joint under different welding sequence were analyzed. Experimental results show that the welding sequence has influence on the residual stress and thermal deformation of T-joint in laser-arc hybrid welding. In comparison of the residual stress and thermal deformation under different welding sequences, it is found that the sequential welding can effectively reduce the welding residual stress, and the thermal deformation of simultaneous reverse welding is minimum. Comprehensive analysis shows that the effect of sequence reverse welding for 304 stainless steel T-joint is the best.