Ni35+11%WC powder was used to enhance the surface performance and prolong the service life of 45 steel gear, providing reference for surface modification of 45 steel gear. Coatings were prepared on 45 steel surface with different laser power and scanning speed by synchronous powder feeding. By comparing the macroscopic morphology, geometry size and dilution rate of different coatings, the hardness under different scanning speeds was tested, and the XRD phase and microstructure of the coatings and sections were analyzed by XRD diffractometer and metallographic microscope. The results show that when the laser power was 900 W, the scanning speed was 2 mm/s, and the powder feeding rate was 1 r/min, the coating appeared columnar dendrites and isometric organization composed of γ-(Ni, Fe) solid solution, Mn7C3, Cr23C6, W2C, W and Cr3C2 phase composition. The metallurgical combination between the coating and the substrate was good, The highest hardness of the coating was 786.6 HV(2 N loading force), and the average hardness was 737 HV, The average hardness of the coating was 2.81 times higher than that of the substrate.