Abstract: In order to reduce the influence of disturbances on the stabilized platform of seeker, an improved double integral sliding mode controller(DISMC) based on extended state observer(ESO) was proposed in this paper. Firstly, the second order extended state observer was used to estimate the unknown disturbances of the system. Secondly, a double integral sliding mode controller was adopted to achieve low steady-state error tracking; meanwhile, the improved power reaching law was adopted to reduce the chatting magnitude. Finally, the performances of tracking and disturbance rejection rate were carried out on the stabilized platform of seeker. The results showed that compared with the traditional PI controller based on disturbance observer(PI-DOB), when the system tracked the trapezoidal wave at 3()/s, response time of LOS rate was reduced by 48 ms, and the standard deviation of tracking error was reduced by 0.013 1 ()/s with the proposed controller. Meanwhile, the turntable generated a periodic motion with sin(t), 3sin(5t) and 7sin(2t) respectively to simulate the motion of the carrier, the disturbance rejection rates were increased by 2.91%, 0.45%, 0.7% respectively. In conclusion, the DISMC-ESO has better performance in dynamic response and disturbance rejecting for stabilized platform of seeker.