Wet dual clutch pressure control system characteristic is one of the key point for the DCT transmission research and development. Considering the hydraulic resistance, hydraulic inductance, hydraulic inductance and flow force, a clutch hydraulic system model and the components dynamic calculation model were built. The AMESim software was used to simulate the dynamic performance. The test and simulation results have the same phenomena. It is shown that the clutch filling speed is not monotonic to the mainline pressure for the clutch P-VFS spool flow force. Choosing right mainline pressure can improve the clutch filling and response speed.