8 mm thick 2219 aluminum alloy plates are welded by friction stir welding technology. The stress characterization and stressrelieving of 2219 aluminum alloy friction stir welded joint is studied by using a self-developed high frequency induction heating device,the test temperature is set as 90 ℃,140 ℃ and 190 ℃ respectively. Through measuring the longitudinal and transverse residual stress of weld before and after heat treatment by using X ray diffraction method,the microstructure and mechanical properties of welded joints are analyzed. The results show that peak value of longitudinal residual stress reduces significantly after high frequency induction heat treatment,which declines by 51.3% at the temperature of 190 ℃ HT,and the range of residual tensile stress narrows. As temperature of high frequency induction heating drops,the effect of stress-relieving decreases. Microstructure,microhardness and mechanical properties of welded joints do not change obviously before and after heat treatment. The high frequency induction heating technology can reduce the welding residual stress effectively,at the same time does not change the mechanical properties of welded joint.