Abstract: The results show that the peak temperature remains at 500℃ in the FSW process and the highest temperature point appears in about 5 mm behind the tool. The residual stress of FS welded joint is mainly longitudinal stress. The longitudinal stress in the vertical direction of weld presents M type and the maximum is about 150 MPa. In the FSW process, when the rotation speed of the tool is constant, with the increasing of welding speed, the temperature decreases and the peak value of longitudinal residual stress increases. When the welding speed is constant, with the increasing of rotation speed, temperature increases. With the increasing of rotation speed, the distribution of longitudinal residual stress becomes more homogeneous.