The work aims to study the influence of different WC contents on the wear resistance of Ni-based WC composite coatings deposited by the plasma transfer arc, so as to expand the use in practice. Ni-based composite coatings were sintered by plasma transferred arc welding with 20%, 30%, 50% and 60% content. Cross-sectional friction wear tests were conducted with multifunctional friction and wear tester made by Bruker corporation. By observing morphology, friction coefficient, cross-sectional area and microstructure of wear track, the influence of WC content on the wear resistance of composite coating was investigated. The results indicated that the wear resistance of Ni-based WC composite coatings deposited by the plasma transfer arc welding rose while the content of WC increased; meanwhile the wear resistance of the base near the fusion zone was also improved. When the content of WC was less than 50%, adhesive wear and oxidative wear mainly existed. When it exceeded 50%, adhesive wear and abrasive wear mainly happened. Due to the existence of WC and the continuous generation of wild phase, the wear resistance of composite coating will be continuously improved with the enhancement of the WC content. For the sake of performance and cost, WC of 50wt.% is more suitable for practical applications.