In view of the characteristics of numerical control turntable servo system directly driven by permanent magnet ring torque motor, which is susceptible to load disturbance and parameter variation, a dynamic-integral sliding mode position controller is designed. Dynamic sliding mode control means making differential operation to switching function of conventional sliding mode control, thus, a new switching function can be obtained. The discontinuous terms are transferred to first or higher derivative of control quantity. Therefore, the dynamic sliding mode control law is continuous timely, and then the chattering can be effectively reduced. Meanwhile, in order to ensure the steady-state accuracy of system, the integral term is introduced in the switching function to realize dynamic integral sliding mode control. The simulation results indicate that dynamic-integral sliding mode control of permanent magnet ring torque motor has favorable dynamic response and strong robustness, and it is effective to weaken the chattering.