The system of three level cartridge valve was modeled by AMESim and the mathematical dynamic equations of liquidcharge cartridge valve and liquiddischarge cartridge valve were established. The inlet pressures of liquidcharge cartridge valve and spool displacement of liquiddischarge cartridge valve were researched mainly. The results show that the main factors which affect the liquidcharge cartridge valve are the spring stiffness, spring pretightening force and damping coefficient; the main factors which affect the transient and steady opening of liquiddischarge cartridge valve are the spring stiffness and spring pretightening force; the main factor which affects the closing characteristic of liquiddischarge cartridge valve is damping coefficient.