The tangential grinding force of the grinding wheel was calculated by measuring the power of the electric spindle during the machining and no-load of the inner surface grinder SUU600A; the normal grinding force was calculated according to the empirical algorithm, and the influences of grinding wheel linear speed, feed rate, grinding depth on the normal grinding force were analyzed, and the change trend of the normal grinding force was summarized; a fuzzy PID control method for grinding force in the CNC grinding process was proposed. The results show that when using the fuzzy PID grinding force control system, the grinding force can be adjusted in real time to keep it constant or within a predetermined range, so the grinding efficiency is improved; the improvement of grinding efficiency is verified by experiments.