<p>In the process of 2219 aluminum alloy thick plate FSW, the residual stress of the joint is large, which will reduce the performance of weldment. The residual stress distribution law of 2219 aluminum alloy thick plate FSW joint is explored based on simulation in this paper. The tool model with total elements of geometrical characteristics is established, the material parameter and friction coefficient varying with temperature are considered. The local fine mesh generation and quality scaling technology are used to improve the computational efficiency. Finally, the simulation of residual stress in FSW joint of 2219 aluminum alloy thick plate is realized based on ABAQUS/CEL. The size of the test sample is determined according to Saint Venant principle, and the validity of the model is verified by the X-ray diffraction method. The residual stress distribution law of the joint is analyzed. The results show that the established model can accurately simulate the residual stress distribution after welding, and the transverse residual stress is always lower than the longitudinal residual stress. The longitudinal residual stresses on both sides of the joint are asymmetrically distributed, and the residual stresses on the advancing side are higher than those on the retreating side. This research result provide key theoretical basis for optimizing the welding parameters of thick plate FSW.</p>