Abstract: The four-ball friction and wear tester was used to investigate the tribological properties of complexing friction modifiers of molybdenum dialkyl dithiophosphate and nitrogen-molybdenum complex, phosphate, N-containing borate ester in CF-4 15W-40 diesel engine oil. A uniform design method was used to design the test. The partial least squares quadratic polynomial regression method was introduced to establish the regression model of multi-independent variables on the multi-dependent variables. The relationship between independent variables of temperature and additives content and the dependent variables of friction coefficients at low, medium and high load and wear scar diameter (WSD) were created, resulting in the optimum formula of the complexing friction modifier, which was verified by experiment. The results show that the optimum composition of complexing friction modifier is consist of molybdenum dialkyl dithiophosphate and nitrogen-molybdenum complex, phosphate, N-containing borate estethe as 0.779 9%，1.200 0%，0.662 9%, respectively. The optimum formula can effectively reduce the friction and wear: more than 43% reduction of the friction coefficient and 47% decrease of the WSD.