Abstract: By means of an established three-dimensional heat finite element mathematical model and software ANSYS, the temperature distributions of friction stir welding process (the tool inserting and the stable welding stage) on 14 mm thick 2219 aluminum are calculated. Calculated results indicate that in the beginning of the stage, the variations in temperature have nothing to do with the welding speed and the biggest temperature rise rate presents; in the stable welding stage, the temperature gradient presents different distribution along thickness direction of the plate, which is wide and high at the top while narrow and low at the bottom; in both of stages, the more the rotary speed is, the higher the peak temperature of weld is. The temperature field simulation results are basically consistent with experimental results, which come to conclusion that the mathematical model is correct.