Taking plexiglasses the grinding and polishing object， a robot grinding and polishing systemsis established， which is composed of robot offline path planning and online force control. An active and passive compliance control grinding and polishing model is set up by analyzing the grinding and polishing tool force in process of machining according to flexible mechanism and active compliance control. The gravity compensation algorithm based tool load is proposed by tool gravity calculation， which is for eliminating gravitational disturbance in the grinding and polishing process. A novel explicit force control strategy based on impedance inner loop control is proposed，and the tracking with no static errors about the grinding and polishing force is implemented. The experimental results show that the robot achieves a relatively constant force control effect by modifying the robot trajectory through calculating the difference between reference force and actual force.