In recent years, global warming, acid rain and other environmental problems are becoming more and more serious, and a variety of fuel resources made from fossil fuels are also facing depletion. As a way to solve these problems, biofuels have attracted much attention. The biofuels are fuels based on biological resources produced by plants, which have less pollution to the natural environment.In this study, the experiment has been carried out to determine the influence on combustion characteristics and exhaust emissions for a small diesel engine by using the fuel of bio-ethanol addition. The fuels are used in this study for five types by changing of the ethanol addition volume percentages from 5% to 25% in the blended fuels. The combustion behaviors, such as burning pressures, heat release rate and emissions (CO, HC, NOx, Smoke) are observed.The main conclusions are as follows:(1) The emissions of HC and CO increase by using the fuel of bio-ethanol addition than that of the light oil.(2) It is possible to reduce the NOx and smoke emissions by using ethanol-light oil blended fuels under the low load.(3) The most suitable conditions of ethanol addition exist by using ethanol blended fuels against the load conditions
