In this paper, Co-based WC composite coating was prepared by laser cladding on the surface of high speed steel (HSS) tools damaged for numerical control machine tools. The results show that the interface metallurgical bonding between HSS substrate and repair layer is good without obvious defects. The repair layer is mainly composed of a Co-based FCC crystal structure and three types of carbides. The microhardness is about (1625±63) HV, which is 364.3% higher than that of the HSS substrate. The average friction coefficient is 0.65. The wear surface is relatively intact compared with the HSS tool. Cutting experiments show that the HSS tool with the Co-WC repair layer has lower O content on the rake face and better cutting performance.