Abstract:With the development of digital hydraulic technology, performance of the high speed on-off valve have higher requirements, the mechanical properties of high speed on-off valve spool determine the overall performance. The Computational Fluid Dynamics (CFD) model of a high speed on-off valve is established. According to the different working pressure, different temperature, different base diameter, different base angle and different opening of a high speed on-off valve, internal flow velocity field was analyzed. The factors that affect the hydraulic pressure of high speed onoff valve were analyzed under different working conditions. The affecting law of valve opening, the valve outlet shape, valve opening pressure, oil temperature on the hydrauic pressure of valve spool is further researched to provide a theoretical basis for the design of high-speed onoff valve.