Abstract: The electron beam welding of(35CrMnSi steel) was studied. The results showed the appearance of electron beam welded joint was good, and no welding defects were found. The weld was fully austenitized, the rapidy solidified microstructure mainly consists of batten martensite while a small amount of residual austenite. The heat-affected zone can be divided into the overheated zone, normalized zone and slack quenching zone. The microstructure of overheated zone was coarse martensite. The microstructure of normalized zone was the mixture of martensite and bainite. The tensile strength of joint was higher than the base metal and the fracture occurred at the base metal. The weld hardness was significantly higher than the base metal, the bending strength was 1300 MPa, which was better than base metal, and the bending strength increased slightly with beam current. The bending angle of joint was 54°, which was slightly lower than the base metal.