In practical applications, the expansion state observation in self disturbance rejection controllers faces the problem of inability to guarantee estimation and compensation accuracy when faced with significantly changing load disturbances. A scheme is proposed to improve the estimation and compensation accuracy by compensating the load disturbance observed by the load torque observer to the extended state observer. The load torque observer is designed using angle data that can be directly measured in the motor as a known quantity, avoiding the problem of introducing differential errors by using the speed as a known quantity. The simulation and experimental results show that the improved linear active disturbance rejection controller reduces the maximum speed adjustment by 7.24% compared to the traditional linear active disturbance rejection controller, and has better anti load disturbance performance while ensuring the adjustment speed.