The invention discloses a self-sharpening resin binder diamond grinding wheel and a preparation method thereof. The formula of the grinding wheel comprises the following components of, in percentage by volume, 15%-65% of foam diamond, 15%-45% of phenolic resin powder, 2%-15% of chromic oxide, 0%-15% of zinc oxide, 2%-10% of graphite, 16%-50% of silicon carbide, 0%-3% of pore forming agent, 0%-3% of a coupling agent, and 0%-5% of a wetting agent. According to the self-sharpening resin binder diamond grinding wheel and the preparation method thereof, compared with an existing grinding wheel, the self-sharpening resin binder diamond grinding wheel prepared through the method is characterized in that the foam diamond, the pore forming agent, the wetting agent and the coupling agent are added, the effective contact area between the foam diamond and the binder is increased, abrasive particles cannot fall off integrally due to the inlaying effect of the foam structure of the foam diamond and the binder, the diamond grinding wheel is even in consumption in the using process, the finishing frequency can be effectively reduced, good grinding force is kept, meanwhile, the self-sharpening performance of a grinding tool is improved, cutting damage is effectively reduced, and the workpiece surface machining quality is improved.