Abstract:Through 10 different blending ratio of cooking oil biodiesel in a 2-cylinder direct injection diesel engine on the engine bench test, studied the gutter oil performance, fuel economy and emissions of biodiesel with the variation of ratio of blending. And, according to the results of the experiment under the condition of moderate load which diesel engine is widely applied, using the genetic algorithm calculated the optimum blending ratio by MATLAB simulation. Optimization results show that in the medium load cases, cooking oil biodiesel and diesel optimum blending ratio is 21:78. At this point, the engine power reduction is not much, a 4.43% increase in fuel consumption rate, NOX emissions decreased by 5.01%, the smoke emission reduced by 20.76%, so its comprehensive performance achieved the optimal.