By taking a long focal length oblique CCD camera as an object of study, a multiple loop control scheme based on the high gain observer was proposed to improve the position accuracy of auto-collimating auto-focusing lens barrel in a high dynamic state. Firstly, a mathematical model was established according to the open-loop amplitude-frequency characteristic curve of a depression angle control system. The feasibility of control scheme was analyzed by the control theory and the simulation tests were adequately performed. Then the reliability of control scheme was further validated through the practice control system. The experimental results show that the high gain observer can estimate the angle speeds and angle acceleration well. As compared with the double closed loop control method, this proposed control scheme reduces the maximum position control disturbance error by 96.3% and ensures the requirement of lens barrel positioning precision within ±0.05° .Hence the new control method is valuable in practical engineering applications.