The steady-state error of the feed system control is a key technical problem to ensure the smooth operation of CNC machine tools and processing of qualified products. By establishing the mathematical model of feed drive system in closed loop, and combined with the time domain analysis method, the steady-state error and the influence factors were derived, and specific measures were put forward to optimize decreasing of the steady-state error of the closed-loop system. It improves the feed system of CNC machine tools motion stability, and effectively reduces the positioning error.