In order to utilize the laser cladding technology to achieve the additive manufacturing of the knife blade edge of the die-cutting machine, the laser power, scanning speed and defocusing amount are the influencing factors, and the single-pass laser cladding of WC-reinforced Ni-based mixed powder is performed on the surface of the 45 steel. The experiment was conducted to prepare a single-pass laser cladding gradient coating, and the microstructure structure, defect rate, residual stress and microhardness of the cladding layer were analyzed. According to the analysis results, the microstructure of the cladding layer shows obvious stratification which is conducive to improving the performance of the cladding layer. The defect rate increases with the increase of the scanning speed and the defocus amount, and increases first and then decreases with the increase of laser power. The scanning speed has a significant effect on the defect rate. The difference in temperature between the cladding layer and the substrate and the difference in thermal expansion coefficient between the cladding layer and the substrate during the cladding process are the main causes of residual stress. The influence of each factor on the residual stress is: scanning speed＞laser power＞defocusing amount. The structure of stratified layers helps to reduce the difference of linear expansion coefficient between the cladding layer and the substrate. The microhardness increases stepwise from the substrate to the top of the cladding layer. The microhardness of the top of the cladding layer can reach 70 HRC, which is about 3 to 4 times that of the substrate. It is superior to the actual performance of large-scale use of the imported powder metallurgy carbide die-cutting machine knife blade hardness (63 HRC).