An ultrasonic atomization system was designed by using the ultrasonic atomization principle to study atomized ethanol and it was tested through the inlet in a small swirl chamber diesel engine to find the effect of ultrasonic atomization ethanol in substituting for diesel fuel in diesel engine. During the test, the ethanol supply was calibrated to be 20% of the oil, the amount of diesel fuel supply was changed for load adjustment, and the fuel consumption and emissions performance of the engine were tested under different load with standard rotation speed. The results show that the diesel engine fueled with ethanol/diesel dual-fuel shows stable performance in the work. NOX, CO and soot emissions are lower than the original engine supplied with diesel fuel alone, especially at full capacity with a reduction up to 60% of soot. The energy consumption rate is roughly equal to the original engine, while HC emissions are higher than those of the original engine. 