NOVELTY - A method for producing biodiesel from high acidity oil comprises: (1) adding the oil into reaction kettle of high speed mixing apparatus, adding short chain alcohol and fatty acid methyl ester; (2) adding alkalescent substance into emulsion in (1); (3) preparing potassium hydroxide (KOH) or sodium hydroxide (NaOH) solution and methanol as catalyst, adding into emulsion in (2), refluxing; (4) cooling, separating; (5) distilling the biodiesel coarse product, reclaiming superfluous short chain alcohol; and (6) preparing biodiesel satisfying standard through molecule distilling.    USE - The method for producing biodiesel from high acidity oil is used for renewable energy resource field and large scale industrial production.    ADVANTAGE - Preparation process of the biodiesel from high acidity oil is simple, the condition is gentle, and economical efficiency of the technique is good.    DETAILED DESCRIPTION - A method for producing biodiesel from high acidity oil comprises using (pts.wt.) oil (100), short chain alcohol (20-120), fatty acid methyl ester (1-10), catalyst (0.5-4) and alkalescent buffer substance (0.1-5), and the step involves: (1) adding the oil into reaction kettle of high speed mixing apparatus, adding with short chain alcohol and fatty acid methyl ester, mixing with high speed for 1-4 hours at room temperature to form even emulsion; (2) adding alkalescent substance into emulsion in (1), mixing with high speed for 1-4 hours; (3) dissolving KOH or NaOH solution into the methanol to prepare KOH or NaOH methanol solution with a mass percentage of 8-10% as catalyst, adding into emulsion in (2), performing reflux reaction for 0.5-4 hours at 50-120 degrees C; (4) cooling to 40 degrees C, performing static separation to separate by-product like glycerol of lower layer to obtain biodiesel coarse product; (5) performing normal pressure distilling to the biodiesel coarse product and reclaiming superfluous short chain alcohol; and (6) preparing biodiesel satisfying standard through molecule distilling.