A model for friction and wear calculation of piston ring and cylinder based on contact mechanics was proposed. The two areas, which were generally under starvation lubrication, were emphasized and the effect of the oil film was ignored. Higher temperature caused larger deformation resulting in the increase of contacting asperity, thus the load taken by asperities increased. Frictional heating increased both the contact area and contact pressure. Low speed and high load seemed to cause much plastic deformation resulting in much wear of the cylinder surface. This is an abstract of a paper presented at the World Tribology Congress (Kyoto, Japan 9/6-11/209).