Abstract: The criteria of overcoming low-speed slip-stick phenomenon of third-order system is given by using phase plane method, algebra analyzing method and Lyapunov stability theorem. The relationship between system parameter and low-speed slipstick phenomenon is found, and the condition of choosing the parameter of PID is given, which should satisfy the purpose of overcoming low-speed stick-slip and guaranteeing the stability. This method is simple and easy to implement. It has directive significance to high precision servo system.