In order to improve the defects such as coarse columnar crystals, cracks and pores in the traditional laser cladding coating, the test of ultrasonic vibration assisted laser cladding to prepare Ni-based WC+CeO2 coating on the surface of 42CrMo steel, and the influence of different ultrasonic power on the phase composition, microstructure, microhardness and wear resistance of the coating was studied. The results show that the introduction of ultrasound does not change the phase composition of the coating, the coating phases are all composed of solid solution γ-Ni (Fe), intermetallic compounds Ni3Fe, WC, Cr23C6, M7C3 (M=Fe, Cr)and so on. With the increase of ultrasonic power, the thinning effect of cavitation effect and acoustic current effect on the coating increases. When the ultrasonic power is 350 W, the microstructure of the coating is improved most obviously, the thick columnar crystals at the bottom of the coating disappear, and a large number of small dendrites are distributed in the coating. The hardness curve fluctuates smoothly, and the average microhardness is 1 074.9 HV. The average friction factor is 0.28, and the minimum amount of wear is 8.43×10-3 mm3, which is 27% and 25% less than the coating without ultrasonic vibration.