A mathematical model of wet clutch hydraulic oil supply system and test bench are established to calculate and simulate pressure pulsation of hydraulic components by Simulink simulation. Characteristics of pressure pulsation at pump discharge, filter entrance and exit, relief valve inlet were analyzed. The influence law of the gear pump rotating speed n, the teeth of gear pump z, the diameter of oil tube D, and the relief valve orifice diameter d on pressure pulsation was analyzed. Both the simulation results and the experimental data show that the model can effectively reflect the characteristic of pressure pulsation. Pressure pulsation frequency is mainly determined by the flow pulsation frequency of the gear pump, and the pulse amplitude gets smaller along the oil flow direction. When rotating speed increases, the pressure pulsation frequency and amplitude both increase linearly. For effective lowering of the pressure pulsation, z is recommended to be more than 10, d is recommended to be 2.5 mm, and for better of the oil supply system of wet clutch, D is recommended to be from 25 to 30 mm.