TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The acid catalyst comprises sulfuric acid or p-toluenesulfonic acid.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The grease raw material comprises common vegetable oil or waste grease. The acid value of the grease raw material is 0-200 mgpotassium hydroxide/g. The grease raw material comprises soybean oil, colza oil, cottonseed oil, rice bran oil, corn oil, waste oil and/or acidified oil. The methanol contains 15-30%, preferably 18-25% of grease raw material and acid catalyst contains 1-3% of grease raw material. Preferred Method: The method further comprises (i) installing an overflow tower plate in the rectifying tower, where the upper part of a catalyzing and rectifying tower is connected to a pre-heater with a static mixer; (ii) mixing and pre-heating the grease raw material, acid catalyst and small amount of methanol, and passing the mixture to the upper part of the rectifying tower; (iii) pre-heating the remaining methanol, and passing the methanol to the lower part of the rectifying tower, and preheating the methanol at the bottom part of the catalyzing and rectifying tower, and obtaining methanol vapors under certain temperature, where the methanol vapors moves towards the upper part of the catalyzing and rectifying tower, and completely reacting with the grease raw material containing acid catalyst set on several overflow tower plates; (iii) reacting crude methyl ester with the methanol vapors, and obtaining a semi-finished product containing methyl ester with no glycerides and fatty acids; (iv) completely reacting the methanol vapors and overflowing grease raw material under the presence of acid catalyst; (iv) discharging the methanol vapors and water generated by the reaction from the upper part of the tower, allowing the product containing glycerol, acid catalyst and partial water to settle at the bottom of the rectifying tower; (v) separating small amount of methanol, water, acid catalyst and glycerol phases by a separator; and (vi) refining the semi-finished product to obtain biodiesel. The acid catalyst comprises fluid acid catalyst monomer or mixture. The reaction temperature is 70-130 degrees C, preferably 95-100 degrees C.