The groove fillet of O-ring seal is beneficial to the installation of the O-ring and the retaining ring,which can prevent the O-ring or retaining ring from being scratched by the sharp edge to affect the reliability of the seal.The groove fillet radius also has a great influence on the sealing performance of the O-ring.Taking the fillet radius of groove edge as a variable,a two-dimensional axisymmetric model of O-ring seal structure with and without retaining ring was established by using the finite element analysis software.The sealing performance of O-ring under static seal and dynamic seal under 35 MPa medium pressure was analyzed.The von Mises stress,contact pressure and extrusion of O-ring and retaining ring with different radius were compared.The results show that the O-ring seal with retaining ring can meet the sealing requirements under the action of 35 MPa medium pressure,and the combined use of retaining ring and O-ring can effectively reduce the influence of groove fillet radius on O-ring sealing performance.The stress at the extrusion position increases with the increase of the fillet radius of the groove edge.The larger the fillet radius of the groove edge,the greater the stress increase at the extrusion point.Therefore,when it comes to dynamic seal,in order to ensure that the O-ring and retaining ring are not scratched by groove edges and that the retaining ring is subject to small stress at the extrusion point,the fillet radius of groove edge should not be too large.The conclusion can be used as a reference for the design of O-ring sealing groove with retaining ring.