Pressure reducing valve as an important component of hydraulic system, its main role is to make the system outlet pressure is always lower than the inlet pressure level to maintain the system outlet pressure stability, and the system outlet pressure from inlet pressure and flow fluctuations ; However, once the valve sealing surface leakage occurs, not only affect the normal production, but also cause the loss of hydraulic oil, polluting the environment; in the marine hydraulic system, the valve as the main control element, the importance of its sealing is not to be underestimated of. 1, the static pressure relief valve seal failure analysis of the problem After a joint research and analysis of relevant experts found that the pressure relief valve between the valve sleeve and the connection between the seal is mainly relying on the connection between the sleeve and the inner wall of the O-ring for Circumferential seal, the seal once effective, the external leakage is inevitable. 2, pressure relief valve to solve the problem of sealing measures (1) to improve the sealing surface quality relief valve. (2) to ensure the amount of compression valve seal O-ring compression. (3) increase the valve seal. (4) Reduce the friction between the O-ring of the pressure reducing valve and the sealing surface.