NOVELTY - A method for preparing biodiesel through reverse micelle catalyst comprises: (a) acidifying waste oil; (b) preparing reverse micelle catalyst system; (c) catalytically reacting micelle; (d) decompressing and distilling, putting biodiesel coarse product in the hog still; removing water content at normal pressure; and collecting distillation of 200-250 degrees to obtain pure biodiesel.    USE - The method for preparing biodiesel through reverse micelle catalyst is used for reclaiming different waste oil such as leftovers of oil factory, catered oil, hogwash oil, soap-stock, and pigwash oil.    ADVANTAGE - The method for preparing biodiesel through reverse micelle catalyst is simple and credible; the productivity effect is high and energy consumption is low; and the waste discharge is little.    DETAILED DESCRIPTION - A method for preparing biodiesel through reverse micelle catalyst comprises: (a) acidifying waste oil, putting the measured waste oil in hydrolyzed pot; adding sulfuric acid with density of 60-80%; the addition of sulfuric acid is 1-10% of waste oil and boiling by steam at 0.5-2 hours so that soap-stock is acidified; after stewing, discharging lower waste water and middle layer; washing upper oil layer by brine; the added brine quantity is 20-40% of the weight of material in the pot; boiling for 5-60 minutes through steam; after stewing, discharging lower waste water; the upper is acidified oil; (b) preparing reverse micelle catalyst system, mixing surface active agent, water and lower carbon alcohol; the dosage of surface active agent is 0.5-10% of the waster oil weight; the dosage of alcohol is 10-50% of acidified oil weight; after evenly stirring at 1500-3000 rotation/minute, gradually adding oil to form reverse micelle catalyst system; (c) catalytically reacting micelle, heating the prepared reverse micelle catalyst emulsion through stirring and reflowing for 3-10 hours; after stewing, discharging the lower acid water and collecting; washing saturated brine for 2-3 times; the addition of water at each time is 30% of coarse fat acid quantity; discharging lower waste water; repeating operation until the discharged waste water shows neutral; the lower layer is the water layer containing glycerin; after processing water, circularly using; the upper layer is coarse biodiesel; dehydrating and distilling; (d) decompressing and distilling, putting biodiesel coarse product in the hog still; removing water content at normal pressure; collecting distillation of 200-250 degrees to obtain pure biodiesel.