Abstract: In current lubrication analysis of piston ring-cylinder liner frictional pair for internal combustion engine, the lubrication status between the piston ring and cylinder liner is supposed usually to be the sufficient lubrication or fixed poor lubrication, not determined by the analysis of actual formed condition of lubrication oil film. In this paper, a multi-cylinder four-stroke internal combustion engine is taken as the studying objective.Based on the equations of lubricating oil flow-rate and volume change of control volume, the flow model of lubricating oil between the piston ring and cylinder liner was established. The effect of different lubricating oil supply quantity at the entrance of piston ring on the lubrication performance of piston ring-cylinder liner frictional pair was analyzed. The results show that the lubrication condition at the entrance of piston ring had obvious effect on the lubrication performance of piston ring-cylinder liner frictional pair. The more the lubricating oil supply quantity at entrance, the larger the minimum oil film thickness of piston ring-cylinder liner frictional pair, and the less the maximum oil film pressure, micro-bulge acting force, frictional force and power loss of piston ring-cylinder liner frictional pair. The lubrication performance of piston ring-cylinder liner frictional pair can be improved remarkably by increasing the supplied oil film thickness in the condition of less supplied oil film thickness at entrance.