Abstract: By means of electronic probe test,we explore experimen-tally the microstructure characteristics and diffusion behavior of the friction welded joint of T2 copper and 1Crl8Ni9Ti stainless steel during the electric field post weld annealing treatment.We determined distributions of chemical elements in friction welded joints undergoing pest weld heat treatment and calculated the interdiffusion coefficient and diffusion activity energy of the dominating elements around the friction welding interface of the two different materials during the heat treatment process both with and without the electric field respectively.The relationship between the intensity of electric field and the diffusion activity energy is obtained and analyzed.The diffusion zone of Fe widens in the presence of electrostaticfield and the diffusion activity energy decreases when applying the external electrostatic field.Moreover,the diffusion zone of friction welded joint after annealing treatment widens with the increase of electric field in-tensity,and the electrostatic field has greater influence on the diffusion distance and diffusion activity energy when the specimen is connected to the cathode of the power supply.