With the development of industries such as mining and urban infrastructure construction, higher requirements have been put forward for the wear resistance of mining WC-Co mining tools. It is a feasible new idea to enhance the wear resistance of WC-Co mining tools by adding diamonds. In the process of sintering the diamond-WC-Co composites, the cobalt phase acts as a catalyst to accelerate the conversion of diamond to graphite. In order to study the influence of Co on the degree of graphitization of diamond in composites, spark plasma sintering (SPS) was used to prepare diamond-WC-Co composites, the degree of diamond graphitization in composites was analyzed, and the grinding wheel method was used to study the wear performance and wear mechanism of the composites. The research indicates that diamond in the diamond-WC-Co composites can play a toughening effect; Increasing Co content will promote the densification process of the composites while reducing the hardness of the composites; As the Co content increases, the wear resistance of the composites becomes worse. During the experiment, the WC-Co matrix was first removed by abrasion, and then the diamond was worn. Diamond will enhance the wear resistance of the composites.