In order to study the influence mechanism of WC microstructure evolution on crack generation in composite coating, three Ni50A/WC composite coatings were prepared by single-layer laser cladding, transition layer gradient cladding and double-layer cladding. The morphology and structure of coating, crack generation characteristics, and the causes of crack were analyzed. The influence of WC microstructure evolution on crack generation was then explored. The results show that the influence of microstructure evolution of WC by different cladding methods on crack generation is mainly caused by internal cracking of residual WC particles. Compared with the monolayer cladding coating, the content of residual WC particles decreased by 32.7% and 37.9% due to the absorption of more energy by the powder of double-layer cladding and gradient cladding coating, and the source of cracks in the coating was reduced. In addition, the mass fraction of W element in eutectic compounds decrease from 0.534 of monolayer cladding coating to 0.417 of double cladding coating and 0.386 of gradient cladding coating, which reduced the concentration of hard phase elements, composition segregation and cracking sensitivity of coating. This research has certain guiding significance to improve the cracking of laser cladding composite coating and improve the yield of composite coating.