Abstract: PID controller is widely used in most projects, but its weakness is more and more fatal with the development of the stabilization precision. An active disturbance rejection controller (ADRC) based on system identification was proposed to control complex opto-electronic platform which can be described by exact model. Firstly, the system model joined friction and structure resonance models were established in order to simulate full practical states in Matlab. Secondly, the rank of system was confirmed by AIC and the model of system was confirmed by linear least square method, and then the model was transformed into the first visible standard type. Finally, an active disturbance rejection controller was designed. The weakness of PID was conquered by 4th Tracking-Differentiator (TD), 5th Extended State Observer (ESO) and Nonlinear States Error Feedback (NLSEF). Take some complex opto-electronic platform as an example, a series of simulated contrast tests between ADRC and PID were carried out. The results showed that the overshoot was reduced from 1.8% to 0.9%,and the maximum tracking error was reduced from 0.03()/s to 0.013()/s. ADRC had a faster response with a smaller overshoot than PID. This indicates that ADRC achieve control more accurately than PID.