In the dynamic sealing device, friction and wear are important factors affecting the damage of O-ring. The degree of wear depends mainly on the amount of friction. When the liquid pressure is small, the size of the O-ring friction depends on its pre-compression amount. When the working liquid is under pressure, the friction force increases with the increase of the working pressure. In cases where the working pressure is less than 20MPa, the linear relationship is approximate. When the pressure is greater than 20MPa, with the increase of pressure, the increase of contact area between O-ring and metal surface is gradually slow, and the increase of friction force is correspondingly slow. Under normal circumstances, the service life of the O-ring will be reduced by the approximate squared relationship with the increase of the liquid pressure.