In order to improve the sealing performance of sealing ring on flat gate valve that used in Christmas tree,a new type of selfadapted sealing structure with sawteeth at the edge of sealing ring body was designed on the basis of Spring seal.The working condition of sealing ring was simulated by finite element analysis method,and the influence of the characteristic parameters of selfadapted sealing structure on sealing performance of sealing ring was analyzed.The distribution rule of contact stress between sealing surface under different structural parameters of selfadapted sealing ring was obtained,and the new sealing structure was optimized.The results show that the maximum contact stress in the sealing surface is increased with the increasing of the number of sawteeth and the edge angle,and decreased with the increasing of the valley angle.The maximum contact stress of the new sealing structure is 15 times higher than that of the conventional Y-ring when the number of sawteeth is 4,the edge angle is 20°,and the valley angle is 33°.The contact stress between the sealing surface is much higher than that of the conventional Y-ring,and the sealing performance of the sealing ring is improved.