The hydraulic system driven by the motor has the advantages of good reliability, convenient speed regulation and high efficiency, while the hydraulic system driven by the threephase permanent magnet synchronous motor is superior to the hydraulic system driven by the asynchronous motor in efficiency and speed control accuracy. Based on the mathematical model of the hydraulic system of threephase permanent magnet synchronous motor, the characteristics of oil viscosity, the effective volume modulus and the nonlinear frictional force of three nonlinear factors in hydraulic system were considered, and the performance changes of the system were analyzed with Matlab/simulink software. The correctness and validity of the model are verified by simulation experiment, which provides a reference for the study of the performance of the hydraulic system of the permanent magnet synchronous motor.