The effect of cBN particle size and content on composite electrodeposition was explored to improve the high temperature wear resistance of Ni-cBN composite coating. Ni-CBN composite coatings were prepared by adding different sizes (~0.5 μm, 3.0 μm, 10 μm) and content of cBN particles into the electrolyte. The composite amount of the coatings were measured by dissolving-weighing method. The microstructure, microhardness and high-temperature wear resistance of different composite coatings were evaluated by scanning electron microscope (SEM), micro-hardness tester and ball- disc wear test at 600 ℃, etc. The results showed that the particles tended to agglomerate slightly and the composite amount of cBN in the coating was difficult to greatly increase when the size of cBN particle was 0.5 μm. It would help to increase the composite amount of cBN to a certain extent if 3.0 μm or 10 μm cBN particles were chosen. In general, the higher composite amount of cBN and the larger size of particle, the average hardness of composite coating was higher. However, the particle distribution uniformity in the composite coating with 3.0 μm cBN particles was better under the similar composite amount. Compared with the pure Ni plating, the cBN particles dispersed in the Ni-cBN composite coating increased the coating hardness and improve the wear resistance of coating. For the composite coatings with small particles (~0.5 μm), the friction coefficient was slightly lower but the adhesive wear was more serious. Meanwhile, the composite coatings with large particles (~10 μm) had higher roughness and mainly suffered from abrasive wear. In summary, the size and content of cBN particles in the electrolyte directly affected the composite amount and wear resistance of the coating. When the size of cBN particles was ~3.0 μm and the composite amount of cBN was controlled to 40.5 vol%, the microhardness of Ni-cBN composite coating was above 600HV, and the high-temperature wear resistance was better.