Abstract: Based on an external electric field improving superplasticity of materials and the feasibility of isothermal superplastic solid state pressure welding of steel and copper alloy, a new technology of electro-superplasticity solid-state pressure welding is developed, which has an important value and prospects for industrial applications. The results show that 40Cr and QCr0.5 can be welded with the application of an external electrical field 0~3 kV/cm under the condition of non-vacuum, non-shield gas, welding prepressure of 56.6 MPa, initial strain rate of 1.5×10⁴/s, pressure welding temperature of 710~800℃ and pressure welding time of 0~8 min. The tensile strength of the joint is up to or exceed that of QCr0.5 base metal, and the expanded rate of QCr0.5 does not exceed 4%, and welding joint of 40Cr and QCr0.5 has formed a good metallurgical bonding when the electric field intensity is 3 kV/cm.