Spring energized metal C ring is an excellent static sealing component. To study the structural effects on C ring’s mechanical properties and contact performance of the sealing interface, a three-dimensional model of the C ring was established and its mechanical properties and sealing mechanism were analyzed by finite elements method. The simulation results were validated by the compression-resilience test.Results show that the contact area of C ring is larger at the unloading stage than that at the loading stage, which indicates that C ring at the unloading stage has the same sealing performance under a relatively lower load. The coil spring offers C ring a good compression-resilience property to response to the fluctuation in working condition. The silver lining makes a good match between the contact interfaces of flange and C ring. The alloy lining plays a role in protecting the silvering lining and transmitting the contact force smoothly.