Abstract: When the cartridge valve was at rest, the valve core and valve sleeve were stuck due to static friction. In the moving state, the valve core and valve sleeve worn out due to the valve core’s differential pressure and micro offset. Therefore, a cartridge valve spool with a guide slot was proposed. A CFD optimization simulation model of the cartridge valve spool and sleeve clearance was established based on the gap flow and hydraulic clamping analysis. The N-S equation, Bernoulli equation, and clamping force equation were combined to obtain the derivation of the clamping force between the spool and the sleeve. Based on CFD simulation and analysis, the shear stress and pressure distribution patterns of different model gaps were compared before and after the change. The corresponding clamping force was inferred from the tangential pressure distribution of the gap. The results compared the shear stress and pressure distribution between the new spool and the original spool. The results showed that the shear stress of the original spool fluctuated around 12 000 Pa at an inlet pressure of 12 MPa, which was larger than the shear stress of the new spool of 4 200 Pa. The shear stress of the original spool fluctuated around 7 200 Pa at an inlet pressure of 8 MPa, which was greater than the shear stress of the new spool by 3 000 Pa. Furthermore, the fluctuation range of the original spool was much larger than that of the new spool. The new spool in the valve sleeve between the applied force was smoother and had lesser wear. The study results provide theoretical guidance and basis for cartridge valve optimization, as well as reducing energy loss and improving lubrication conditions.