Solidworks and Workbench were used to perform the static analysis and air tightness analysis on the designed sealing structure of the composite pipe plugging head under ultrahigh internal pressure of 100 MPa.Through theoretical modeling and simulation,the designed composite pipe sealing structure was checked and analyzed,the material selection and structural optimization were performed.The theoretical feasibility,as well as the material,structure and other conditions that need to be met to achieve the seal were discussed.The results show that under ultrahigh internal pressure of 100 MPa,the HDPE matrix composite pipe with an inner diameter of 100 mm and a thickness of 11 mm can theoretically achieve sealing by using the improved plugging structure and selected materials.The material safety factor can be guaranteed within 3 to 5,and the seal safety factor can be guaranteed within 2 to 4.