A sliding mode control (SMC) with improved exponent reaching law based on disturbance observer (DOB) is proposed for the robot control, to solve the problem of robot system which is vulnerability to external interferences and has some uncertainties. The disturbance observer (DOB) would detect and compensate external disturbances and uncertainties in the robot system, so that the movement of the robot would be in accordance with the desired trajectory. Besides, a variable exponent reaching law is designed to reduce the chattering phenomenon in sliding mode control (SMC). The simulation results demonstrate that sliding mode control based on disturbance observer can estimate the uncertainties and external interference of the robot accurately, and reduce the chattering effectively, the robot actual trajectory is consistent with the desired trajectory, be able to achieve precise control and excellent control performance. A disturbance observer (DOB) was designed and introduced into the sliding mode control of the robot system to estimate the uncertainties of the robot system and the external interferences in this paper. It makes compensation to modify the system, so that the movement of the robot will be in accordance with the desired trajectory. Besides, a sliding mode control strategy based on variable exponent reaching law has been designed to reduce shaking vibration, to achieve excellent control performance. The simulation results show that this method is effective to reduce the chattering of the robot sliding mode control and make the robot move as the desired trajectory, which improves the precision of control greatly and achieves excellent control performance. Sliding mode control (SMC), also known as variable structure control, in essence, is a special nonlinear control, and its nonlinear is reflected in the non-continuity of control. Due to the properties and parameters of the SMC just depend on the design of the switching hyper plane and have nothing with the external interferences, so that the SMC has good robustness. The advantage of sliding mode control is able to overcome the systematic uncertainty, and has good robustness for disturbances and unmodeled parts, especially suitable for the control of nonlinear systems. Because of SMC with the characteristics of simple algorithm, fast response and robust to external noise and parameter perturbation, SMC has been widely applied in the field of robot control. Sliding mode control applied to robot control field should to be solved first is the chattering problem, due to the impact of the incomplete model of robot system and external interferences, there is always some certain delay and lag. The delay and lag will not make the actual sliding mode motion to be happened in the reserved switch plane, but cause a high-frequency vibration in the vicinity of its both sides, a phenomenon known as chattering of the sliding mode control systems. Chattering generation will affect the system