Abstract: To make the complicated process of heat and force of friction stir welding to be simulated more close to the actual state, we established the three-dimension mathematical model of stirring friction welding process, and analyzed thermal process and temperature field distribution of friction stir welding of 2219 aluminum alloy by means of the finite element method with 3D coupled model. Numerical simulation results show that, the temperature gradient of weld is different which the upper side is more compact than lower side and the advanced side is more compact than back side. The highest temperature is located at the transition zone of the back side between the stir-pin and the stir-head shoulder, the temperatures on the retreating side is higher than that on the advancing side, and it will be assured of tight weld if the temperatures of the area on the bottom of stir-pin are in excess of the recrystallization temperature of 2219 aluminum alloy when welding. At last, the result will provide a support for based research and technology optimization of friction stir welding.