Abstract: Welding is widely used in practical engineering as a metal connection method. Therefore, it is particularly important to predict the distribution of residual stress in the weldment before designing the welding scheme. The multi-layer and multi-pass welding of Q420 high strength steel butt plate was simulated by ABAQUS software,and the distribution of temperature field and stress field was analyzed by sequential-thermal coupling method. The simulation results show that the temperature field in multi-layer multi-pass welding appears at the weld and weld toe,and presents an ellipsoidal gradient distribution behind the welding unit. In multiple thermal cycles, the temperature of the weldment rises sharply when the heat source reaches the vicinity, while the temperature changes gently after the heat source passes and during the cooling stage. At the beginning and end of the weld, the tensile stress concentration is caused by the lack of boundary constraints, and the longitudinal stress is obviously ellipsoidal in the middle area. The transverse stress has the phenomenon of residual stress disappearance and stress redistribution in the multi-pass weld stacking.