The work aims to study effects of different current densitieson the microstructure and properties of Co-Ni-nano Cr3C2 composite coatings and determine optimal current density. Co-Ni-nano Cr3C2 composite coatings were prepared by spray electrodeposition at current densities of 30 A/dm2, 40 A/dm2, 50 A/dm2 and 60 A/dm2. The morphology, composition, structure, hardness and wear resistance of Co-Ni-nano Cr3C2composite coatings were studied with SEM, XRD, microhardness tester, friction wear tester and 3D laser microscope. The microhardness changes of Co-Ni-nano Cr3C2 composite coating and Co-Ni composite coating at different annealing temperatures were compared. The results showed that the addition of nano-Cr3C2 particles did not significantly change the anomalous process of Co-Ni co-deposition. When the current density was 40 A/dm2, the mass fraction of nano-Cr3C2 particles in the Co-Ni-nano Cr3C2 composite coating was up to 12.05%; the surface of the composite coating was rugged and had a nodular structure; the increase of current density had little effect on the composition and phase structure of the composite coating, and the diffraction peaks of Co and Cr3C2 appeared in the composite coating; the microhardness of Co-Ni-nano Cr3C2 composite coating increased first and then decreased with the increase of current density. The highest microhardness value was 585HV0.05 when the current density was 40 A/dm2; the friction coefficient of the composite coating fluctuated greatly when the current density was 30 A/dm2 and 60 A/dm2, but smaller when the current density was 40 A/dm2 and 50 A/dm2. Its wear volume decreased at first and then increased with the increase of current density; when the current density was 40 A/dm2, the wear volume was the smallest and the microhardness of Co-Ni-nano Cr3C2 composite coating increased at first and then decreased with the increase of annealing temperature. When the annealing temperature was 400 ℃, the highest microhardness was 602HV0.05. The deposition amount hardness and wear resistance of nano-Cr3C2 particles in Co-Ni-nano Cr3C2 composite coating change with the current density. When the current density is 40 A/dm2, Co-Ni-nano Cr3C2 composite coating has the highest deposition and the best microhardness and wear resistance. The microhardness of Co-Ni-nano Cr3C2 composite coating can still be maintained at high annealing temperature.