In order to select a reasonable sealing structure of underwater equipment,the sealing performances of Glyd-ring,O-ring,X-ring combination and rectangular-ring in underwater environment were analyzed.The finite element analysis models of four sealing structures were established by ABAQUS.The change of equivalent stress,contact stress and shear stress of four sealing structures under pre-compression stage,variable compression rate and variable external pressure were studied,and the sealing performances of four sealing structures were compared and analyzed.The results show that under the same initial pre-compression rate,the maximum equivalent stress of the rectangular-ring is the largest,followed by X-ring combination,Glyd-ring and O-ring,and the maximum contact stress and maximum shear stress of rectangular-ring is the largest,followed by X-ring combination,O-ring and Glyd-ring.The rectangular-ring shows better sealing performance in the initial pre-compression stage.With the increase of initial pre-compression rate and external pressure,the maximum equivalent stress,contact stress and shear stress of Glyd-ring,O-ring,X-ring combination and rectangular-ring increase,and the stress growth rate of rectangular-ring and X-ring combination is much higher.The rectangular-ring and X-ring is better in sealing capacity,but its equivalent stress and shear stress are too high,which is easy to induce sealing failure.Although the sealing capacity of Glyd-ring and O-ring is not as good as that of rectangular-ring and X-ring combination,their maximum equivalent stress and shear force are small,so their service life is longer when used as seals.