Recently, with respect to an increase of energy consumption, many countries have tried to develop alternative fuels. In the United States, less than 10 percent of motor fuels will be displaced by alternative fuels by year 2010, with about 25 percent of the replacement fuels from renewable resources. But the level of exhaust gas is not decreased to the result of an increase of diesel vehicles. Moreover, emission regulations are being intensified by advanced countries such as America and Europe. Because Biodiesel is similar to diesel fuel, it is essential to judge the environmental and health effects deriving from the use of Biodiesel in diesel engine. Therefore, this research could be conformed whether both Biodiesel 20% and Biodiesel 100% are influenced on emission according to sulfur contents by applying DOC. As a result of using the Biodiesel, this research could be conformed though Nox was increased, CO, HC and PM were decreased, and also estimated to compare diesel fuel with the Biodiesel in accordance with engine performance and emission characteristics.