Due to the effect of the initial interference and medium pressure,the stress and strain gradient of the radial metal seal lip in the interval control valve change greatly,which is easy to cause plastic deformation.In order to study the contact mechanics behavior of the lip of radial metal seal,the circular arc structure of the radial metal seal lip was proposed.Based on contact mechanics,the circular plane contact model of the axial symmetrical structure for the radial metal seal lip was established.The theoretical relationship of the contact mechanics parameters for the radial metal seal lip structure was obtained,and the verification was carried out based on finite element method.The theoretical solution of the contact mechanics parameters for the radial metal seal lip is in accordance with the numerical solution.The average relative errors of contact width,maximum contact stress,initial interference and average contact stress are 8.86%,6.96%,8.88% and 4.33% respectively,which meets the engineering design requirements.The research result shows that the maximum contact stress of the radial metal seal lip is directly proportional to the initial interference,the radial thickness and axial thickness of the radial metal seal lip,and inversely proportional to the arc radius of the radial metal seal lip.Therefor,the maximum contact stress of the radial metal seal lip can be increased by increasing the initial interference,the radial thickness and the axial thickness of the radial metal seal lip.This research result provides the theoretical guidance for the design of the radial metal seal in the interval control valve.