Adaptive PID controller based on back propagation(BP) neural network has many merits like that simple algorithm of PID controller and self-study and adaptive functions of neural network. According the requirements of system output performance, the BP neural network can autoadjust its weights to vary kp, kj and kd. The simulation adjust its weights to vary k results of an electro-hydraulic position servo control system using adaptive PID controller based on BP neural network show that it can get better control characteristics and adaptability, strong robustness in the nonlinear and time vary system. At the same time, simulate results provided a theoretical basis for the design and application of electro- hydraulic position servo control system.