Abstract: Tribology is more important than ever to economy and reliability of automotive engines. A mixed lubrication model has been developed to facilitate the tribological analysis of the piston skirt-liner system. It takes into account the effects of the surface geometry, and the deformations of the piston skirt and liner. The model can be used to find better design schemes to reduce the system friction. Based on the analysis, several improved schemes have been presented for the automotive engine. And the simulation results show that the schemes can obviously reduce the friction of the piston skirt-liner system,the system friction is reduce by 45.5%.