Considering the thermal deformation of cylinder liner, temperature field of cylinder liner, elastic deformation and variable viscosity of lubricating oil, the transient hydrodynamic lubrication model of piston ring-cylinder liner friction pair was established to analyze the effects of operating conditions, roughness direction and size of piston ring-cylinder liner contact surface on friction power consumption and blow-by gas. It was found that the friction power consumption increased and hence the engine efficiency was affected when the speed increased. The combination of transverse roughness direction of piston ring and longitudinal roughness direction of cylinder liner could simultaneously make the blow-by gas and friction power consumption remain at a low level. When the comprehensive roughness was the same, the combination of piston ring surface roughness lower than cylinder liner surface roughness could effectively reduce the friction power consumption.