Abstract: The superplastic welding in an electric field between theromomechanical processed 1.6% C-UHCS and quenched 40Cr steel in atmosphere was conducted based on the analysis of their electro-superplastic weldablity. The results reveal that the performance of 1.6% C-UHCS/40Cr joint can apparently be improved when the sample connects positive,ring connects negative. Thereinto,the superplastic welding of both steels was carried out under the conditions of an electric field intensity of +3 kV/cm, a pre-pressed stress of 56.6 MPa,a welding temperature of 780℃,an initial strain rate of 1.5×10^-4/s and welding time of 20 minutes,and the strength of joint increases by 26.8% compared with that obtained without electric field.