To further improve the control accuracy of the traditional variable structure active disturbance rejection control device and enhance the anti-interference ability of the permanent magnet servo drive system, an improved variable structure active disturbance rejection control strategy is proposed. This method introduces the observation errors of position and velocity into the extended state observer designed based on the variable structure principle to realize the error-free estimation of the state variables, adopts the nonlinear state error feedback control law based on the exponential reaching law design to realize the smooth transition between linear control and nonlinear control, introduces position tracking error on this basis to improve the tracking performance of the servo system. Through experimental analysis, two control strategies of improved variable structure active disturbance rejection control and traditional variable structure active disturbance rejection control are compared. Results show that the position tracking error of the improved control strategy is reduced by about 30% compared with the traditional control strategy. When the load changes suddenly, the tracking error of the traditional control strategy is about 3. 4 times the maximum tracking error before the load change, while the improved variable structure ADRC strategy can still track the given signal accurately.