Abstract: Aiming at the uncertainties such as time varying parameters and external load disturbance of an electro-hydraulic position servo system,the mathematical model of the electro-hydraulic position servo system was established. To improve the tracking accuracy of the electro-hydraulic position servo system,a type of fractional order PID control strategy based on repetitive control compensation was proposed,and the Oustaloup filtering algorithm was adopted to realize the computing of fractional calculus. Then,MATLAB/Simulink software was used to verify the control strategy,the tracking effect with the varied system open loop gain,natural frequency and damping ratio of servo valve,and natural frequency and damping ratio of power mechanism was analyzed. Simulation results show that the proposed control strategy not only improves the tracking accuracy of electro-hydraulic position servo system effectively,but also has strong anti-parameter-perturbation ability and good robustness.