To reduce friction loss between piston rings and cylinder liner is important for achievement of high efficient engine. In this report,the ways of reduction friction of piston rings and cylinder liner are introduced. Effects of shape, coatings and texturing of peripheral of piston rings, surface characteristics of cylinder liner, and engine oil on friction are described. When friction of piston rings and cylinder liner is reduced, lubricating oil consumption is needed to be unchanged or decrease. Therefore in order to design of piston rings, both low friction and low lubricating oil consumption are needed to be taken into consideration.