Abstract: Because the surface properties of tool steel can be improved through nickel-base alloy coatings achieved by electric-spark deposition technology,the nickel-based strengthen alloy coating on the surface of steel 45 is achieved by the hand electric-spark deposition equipment.The effects of the processing parameters such as thickness,hardness and microdefect on the coatings are analyzed.Through some tests,the parameters are optimized and the coating with better properties is obtained.The study indicates that the coating with best combination property,which thickness is about 595 μm,microhardness is 362 HV and there are no apparent defects in the coating,is produced when the output voltage is 128 V,the output power is 1.2 kW,and the argon atmosphere is 5 L/min.