Abstract: The secondary motion of piston is studied by employing the lubrication theory of piston skirt-cylinder wall in conjunction with the dynamic equation of piston. From the point of view of decreasing the secondary motion of piston and friction power loss of piston skirt-cylinder wall tribopair, the design of structure parameters of piston is studied and some important results are obtained. The results can be used in practical piston design.

Key words: Friction power loss, Piston Lubrication, Secondary motion