A self-designed engine lubrication system with 42.1% thermal efficiency was introduced in consideration of that the design of engine lubrication system will affect the fuel economy. Based on the experiments, the oil flow rate of lubrication system was studied, and the influences of different design schemes on engine lubrication system and friction work were compared and analyzed. The results show that the engine friction work decreases and engine efficiency improves by using variable oil pump, low-viscosity engine oil, oil passage orifice, low-tension piston ring and reasonable oil quantities.