Biofuel are energy sources derived from biological material therefore it is renewable and sustainable. Rapid escalation of fuel price, and depleting hydrocarbon fuel reservoir of the word have forced as too look for alternative fuels, which can meet the ever increasing demands of energy and also environmentally accepted. vegetable oil is a better option for diesel engine due to several advantages as renewable, environment-friendly reduce GHG, and global warming. for biodiesel production we use transesterification method which it is the optimum method, because of some reason, such as high conversion, suitable operating condition, direct conversion with no intermediate steps. the importance of use rice bran oil as a raw material is that, first rice is a staple food for most of the world population, second, in some places the rice bran are used as a food for animal or throw away as waste, produced biodiesel from rice bran oil has a high quality, better physical properties which can be improving engine performance, due to better combustion.