Aiming to reduce the friction coefficient of WC-12Co wear-resistant coating, the self-lubricating coating was developed by adding graphene to WC–Co coating deposited via detonation gun spraying. In this study, four powder processes, including wet ball milling, wet mixing, spray granulation, and sintering and crushing, were used to obtaingraphene/WC–Co composite powders. The presence, microstructure and phase composition of graphene in powder and coating were analyzed by means of SEM, EDS and Raman. The mechanical properties of the coating were studied by the microhardness tester and the universal tensile machine. When the spray granulation process is used to prepare the composite powder, a greater amount of graphene covers the surface of the WC–Copowder, and the transparent thin-layered structure of the graphene remains unchanged. The bonding strength and hardness of the resultant coating are approximately 68 MPa and 940 HV0.3, respectively. Graphene modification causes a 25% reduction in the friction coefficient. During the friction process, the graphene constantly forms a lubricating film that serves as an excellent self-lubricating layer.