30.7%。The characteristics of particulate matter emission from the diesel engine burning diesel fuel(D), methanol-diesel fuel(M20) and biodiesel fuel(B) were tested respectively by using a two-stage dilution system and electrical low pressure impactor and the effects of the engine speed, load, as well as the different fuels on the particle size distribution were analyzed. The results indicated that the quantity of PM emission for methanol-diesel fuel(M20) and diesel fuels increases with rotation speed, but biodiesel doesn’t follow this rule on engine performance curve; the peak of PM emission for biodiesel and diesel fuels decreases with load rising at the speed of 2300r/min.On rated power mode, the total volume concentration of diesel is more than that of M20 and B. Compared with diesel, the quantity concentration of biodiesel increases by 30.7%, and the quantity concentration of M20 decreases by 62.8% in nuclear mode.