TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Process: In manufacturing biodiesel, esterifying specifically comprises primary esterifying, adding methanol, sulfuric acid and catalyst into dried oil, stirring and esterifying the mixture at 65-75 degrees C; deep esterifying, adding more sulfuric acid, catalyst and methanol into the reaction kettle, stirring and esterifying the mixture at 65-75 degrees C. Separating biodiesel specifically comprises vaporizing, after recovering methanol, heating the raw oil up to 170-200 degrees C and turning it into gas phase and sending it into a vaporizing tower, vacuuming; fractioning and cooling, fractioning and cooling the raw oil under vacuum condition, obtaining liquid biodiesel. The method also comprises secondary vaporizing, heating up the residual oil in the tower to 170-200 degrees C and turning it into gas phase and heating it in the tower, vacuuming; secondary fractioning and cooling, fractioning and cooling the raw oil under vacuum condition again, obtaining liquid biodiesel. The secondary fractioning and cooling also comprises discharging the asphalt accumulated at lower part of the tower at 100 degrees C. Separating biodiesel specifically comprises decolorizing, after recovering methanol, mixing the raw oil with phosphoric acid, peroxide and water-dissolved decolorant several times; separating and pressing filtrating, freezing the decolorized oil to 30-40 degrees C, then press filtrating it and separating out biodiesel. Dehydrating comprises heating the raw oil at 90-100 degrees C under negative 0.095 MPa; the pressure during recovering methanol is within negative 0.03 to negative 0.04 MPa. The methanol added during primary esterifying is 14-15% the weight of the raw oil, the sulfuric acid added is 2% the weight of the raw oil, catalyst is 1% the weight of the raw oil; during deep esterifying, the methanol added is 5-6% the weight of the raw oil, the sulfuric acid added is 2% the weight of the raw oil, and catalyst is 0.5-1% the weight of the raw oil. During secondary decolorizing, the phosphoric acid added for each time is 0.7-1% the weight of the raw oil, the peroxide added is 0.8-1.2% the weight of the raw oil, and the decolorant is 1-1.5% the weight of the raw oil. Preferred Parameter: The temperature of the raw oil inside the vaporizing tower is 250-270 degrees C under the vacuum at a pressure of negative 0.098 MPa.