Abstract: The surface of U70MnSi and 40Cr were strengthened by a self-made electrical discharge surface strengthening equipment.Hard alloy YG-8 was used as surface coating materials for U70MnSi steel,and FW-1101 welding electrode for 40Cr steel.Composition of strengthened layer was analyzed by XRD.The wear resistance of strengthened layer was investigated by utilization of rolling-wear and rolling-sliding wear.After surface strengthened of 40Cr,the corrosion resistance was examined by anodic polarization and immersion.The results show that strengthened layer of two steels are mixture structure which composed of compound and amorphous structure.Wear resistance of two steels are considerably improved after strengthened under rolling-wear and rolling-sliding wear conditions.Effects of surface mixture structure exceed those of defects and residual stress in strengthened layer,which make corrosion resistance of 40Cr strengthened layer increased.