Abstract:The characteristics of reciprocating sliding seal structure under highpressure water medium were analyzed. The finite element model of U-ring reciprocating sliding seal structure was established based on ANSYS/LS-DYNA software, Mooney-Rivlin model was selected to characterize the hyperelastic rubber, and the Generalized Lagrange Multiplier Method was used as contact algorithm. The simulation of three-dimensional nonlinear contact dynamics of the reciprocating seal structure under different conditions was realized. The effect on sealing characteristics by the main factors such as water medium pressure, moving speed and the direction of sliding rod and contact friction coefficient for was analyzed. The results show that the ring groove, the inner lip and the circle of bottom hole are the main sites of contact stress concentrated on. When the slider moving forward, the velocity and friction coefficient have little effect on seal contact characteristics, while the reverse velocity has large effect on sealing contact stress, the seal failure may occur in this stage.