In recent years, the environmental demage to urban area becomes serious problem due to the exhaust emissions by increasing the number of vehicle. The proportion of diesel vehicle is very high in this country. Exhaust gas emitted from the diesel-powered vehicle is severly affecting to the air quality. In this study, light-duty diesel engine was studied on the improvement of exhaust gas testing method. Therefore the results obtained effective load method among testing method. It is deserve to test of the PM for the environment.