Valvistor valve adopted the flow feedback principle has many benefits including low leakage and big flow capacity and an economical design and has been widely used in hydraulic systems. The underlap in the poppet valve has a significant effect on the flow capacity and static performance. In this paper, the simulation model of valvistor valve was established by using the simulation software—SimulationX. Experiments were made to validate the simulation model. The effects of different underlap in the poppet on performance of the spoolwerecompared. The results show that the underlap in the poppet valve always has to increasethe preopening amount to guarantee the stability, but the underlap will reduce the flow capacity of the valve. The results provide a theoretical basis for the performance improvement of the valve.