Abstract: The experimental factors are supercharger, injector, fuel injection pump and fuel supply advanced angle. The aim of experimentation is to reduce NOx and PM emissions; the way of experimentation is simplex method. It is shown that the simplex method can obtain the best experimentation result by multi-factor diesel engine experimentation method. The results of multi-factor experimentation method show that the big intake air pressure and excessive air ratio of supercharger, suitability of injector properly and the fuel injection pump with a reasonable advanced fuel supply angle properly can reduce the NOx by 19.8% and PM by 26.9%.