Objective To improve the comprehensive performance of WC-Co-Ni nanocrystalline composite coatings. Methods WC-Co-Ni nanocrystalline composite coatings were prepared by pulse electrodeposition, the structure, the surface morphology and the elemental composition were analyzed, microhardness of the composite coatings was tested. The 304 stainless steel and the composite coatings were immersed in H2 SO4 solution of the mass fraction of 5% , the corrosion rate was calculated and their corrosion resistances were compared. Results It was showed that when the pulse parameters were the follows, i. e. , 5 A / dm2 cathodic current density, pulse duty ratio 50% , the pulse frequency of 2000 Hz and the plating time 2 hours, the prepared WC-Co-Ni composite coating formed a nanocrystalline structure. At these parameters, the coating, composed by cubic crystal Ni, hexagonal WC and cubic crystal Co, was smooth and bright without cracks. The WC-Co particles uniformly diffused in the Ni nanocrystalline coating layer and m(Ni) : m(W) : m(C) : m(Co)= 6 : 2 : 1 : 1. WC-Co nanoparticles played an important role to promote nucleation and the grain size was mostly about 20 nm. WC-Co nanoparticles had a strengthening effect on the coating dispersion, making the microhardness of the composite coating reach to 600HV. The immersion test showed that the corrosion rate of the composite coating increased slowly when the temperature raised from 20 ℃ to 80 ℃ , and the corrosion rate was only 0. 4192 mm / a at 20 ℃ and less than 20 mm / a at 80 ℃ . Conclusion The hardness, corrosion resistance and comprehensive performance of the WC-Co-Ni nano-crystalline composite coatings are superior to the traditional 304 stainless steel.