Abstract: In order to improve the accuracy and transient response performance of the directly driven pump controlling system, a fuzzy PID control method based on GA optimization is designed. First, on the basis of the previous research about mathematical model of pump-controlled cylinder, a fuzzy PID controller is designed. Then, the optimization model for fuzzy rules is constructed, and optimal example calculation is performed about a practical directly driven pump-controlling system. Finally, based above researches, step response of a hydraulic directly driven pump controlling system with fuzzy controlling is simulated using MATLAB SIMULINK and tested on the experimental platform. Simulation and experimental results show that the control accuracy and response performance of directly driven pump controlling system have been significantly improved by GA optimization to fuzzy controller.