Underwater flexible connector can solve the problem of unsuccessful connection of underwater oil and gas pipelines due to the deviation of pipeline angle during connection.The sealing structure of the underwater flexible connector is mainly O-ring on the spherical surface.In order to verify the sealing performance of the connector sealing structure under water,the constitutive equation of the O-ring material was calculated and analyzed to obtain the important material parameters of the O-ring rubber material,and from the von Mises stress,contact pressure,and contact width of different contact surfaces,the influence of different pressures on the sealing performance of O-rings was analyzed.The results indicate that the sealing structure of underwater flexible connectors can maintain good sealing performance under different working conditions,and the higher the medium pressure,the greater the contact stress between the O-ring and the sealing groove on the spherical structure,which improves the sealing performance of the connector.The reliability of the O-ring spherical structure in underwater applications is verified through pressure tests.