Abstract: Experimental study on the economy and emission characteristics has important value for serviceability of biodiesel. Based on engine bench test, the brake special fuel consumption and exhaust emissions of the engine when fueled with the four mixing ratios of biodiesel were measured. The results indicate that the biodiesel and blend fuels can be used as alternative fuel in the diesel engine without any modification. As the mixed proportion of biodiesel gets larger, the smoke intensity, HC and CO emission concentrations decrease obviously, which improves the emission characteristics of engine. When 10% or 20% proportion of biodiesel was added for diesel engine, it can reduce the emissions of smokes, HC and CO within economic consumption.