In this paper， ultrasonic motor drive control moment gyroscope gimbal system is described. Importantly， based on sliding control method， a hybrid integral sliding mode variable structure controller（HISMC） is proposed. HISMC guarantees the fast response of the gimbal speed control and improves the robustness of the system under the multi-source disturbance torque. For adjusting the chattering characteristic of the sliding mode controller， a sliding mode observer is introduced to compensate the multi-source disturbance torque， and then reduce the sliding mode switching gain to achieve suppressing chattering. The simulation and experimental results show that the control strategy proposed in this paper can effectively suppress the chattering phenomenon， and the gimbal system has strong robustness under the influence of multi-source disturbance torque.