Abstract: The 40 mm thick OFC plates as the research object welded by electron beam welding with appropriate process parameters. Microstructure and mechanical properties of OFC welding joints were compared with base material. The results show that the welding joint has no apparent surface defects, the weld zone nailed and the microstructure as cast equiaxed crystal grain after the electron beam welding of OFC. The welding joint has good performance, and its hardness, tensile strength and plasticity were equal to that of the base material.