The in-situ WC-reinforced nickel-based alloy ceramic coating is prepared on the surface of a cold die steel with a fiber laser. The inverted metallographic microscope is used to observe the macroscopic morphology of cracks in the cladding layer and the variation of the ice crystal WC with specific powder, specific energy and the powder feeding voltage. In addition, a microhardness tester is used to measure the microhardness of cladding layers. The results show that when the voltage ratio between WC and Ni60 powder exceeds 3∶2, the cracks in the cladding layer cannot be eliminated by the adjustments of specific powder and specific energy. The microhardness of the cladding layer increases with the increase of specific energy, while decreases with the increase of specific powder. Moreover, the increase of the cladding layer conforms to a polynomial distribution accuracy of up to 96%. In contrast, when the powder feeding voltage ratio between WC and Ni60 is lower than 3∶7, WC has nearly no effect on the microhardness of the cladding layer. However, when the powder feeding voltage ratio exceeds 4∶6, the microhardness jumps to 780 HV. According to the influence of the ratio between specific powder and specific energy on the increase and melting depth of the substrate, the process parameters of laser cladding are adjusted to eliminate the cracks of the cladding layer and simultaneously maintain the microhardness at about 800 HV.