The roughness of sliding surface is the direct factor affecting the friction and wear of O-ring surface. Generally, the surface smooth friction and wear is small, so the roughness of the sliding surface value is often very low (ra0.2-.050μm). However, the test shows that low surface roughness (RA below 0.050μm) can also adversely affect friction and wear. This is because the tiny surface is rugged and the necessary lubricant film can be maintained. Therefore, the appropriate surface requirements should be selected. The material of the sliding surface also has an effect on the life of the O-ring. The greater the hardness of the sliding surface material, the higher the wear resistance, the stronger the ability to keep the smooth, the longer the life of the O-ring. This is also an important reason for chrome plating on the surface of the piston rod of hydraulic cylinder. Similarly, it can be explained that the sliding surface made of copper and aluminum alloy with the same roughness has more serious friction and wear on the sealing ring than the steel sliding surface, and the sealing ring with low hardness and large compression is not as durable as the sealing ring with high hardness and small compression amount.