Aiming at the influence of uncertain nonlinear factors such as frictional interference on the control performance of the continuous rotary electro-hydraulic servo motor system, the motor system model and its friction torque model are established in this paper. Combined with controllers, genetic algorithm is used for parameter tuning, and a simplified dynamic flexible variable structure PD composite control strategy based on friction feedforward compensation is determined. The simulation and experimental results show that the simplified dynamic flexible variable structure PD composite controller can improve the performance of ultra-low speed and high frequency response of continuous rotary electro-hydraulic servo motor, which has better control accuracy.