Abstract: In order to reduce the flow force and radial jammed force on the spool and raise the anti-cavitation performance of the spool valve, CFD simulations were adopted to analyze the influences for the forces (include the flow force and radial jammed force) on the spool and the lowest pressure value around the notch by the factors such as the ratio of the areas (the ratio of the flow area through the notch and the flow area through the annular space after the notch), the axial length of the annular space after the notch and the arrangement of the inlet and outlet passages of the spool valve. The result indicates that: along with the increase of the ratio of the areas, the radial jammed forces on the spool increase in one direction and the flow force on the spool decrease in the notch closing direction first and then increase in the notch opening direction; the spool valve has the strongest anti-cavitation performance when the ratio of the areas is 0.5; when the length of the annular space after the notch increases, the variation law of the forces on the spool is the same with the increase of the ratio of the areas but there is the optimum length with which the valve has the best anti-cavitation performance; when the inlet and outlet passages are in opposite direction, the radial jammed force on the spool reduce a lot. This research provides a theoretic base for the designers of the spool valve on board the ship.