The nonmetallic valve spool has the advantages of safety,stability and biocompatibility.In order to expand the application of nonmetallic elastic valve spool in medical waterjet,a check valve spool structure with doubleprotrusion structure of polyurethane material was designed to replace the metal valve spool and the spring,which can achieve the control of the fluid.Based on the nonlinear mechanical response of elastic materials,Ansys Workbench was used to calculate the stress and deformation under the different precompression.The results show that the static sealing effect of the valve spool is the best when the precompression is 0.1 mm.For the elastic valve spool,the position of the maximum equivalent stress and the maximum deformation position are different,which should be considered separately in the design process.The size,processing quality and material properties of the inner ring protrusion will determine the dynamic sealing performance of elastic valve spool.