NOVELTY - Preparation of oxidation-resistant biodiesel involves adding medical stone to waste oil, stirring, filtering, obtaining filtrate, mixing with mixed liquid comprising anhydrous methanol and sulfuric acid, obtaining raw oil, heating, refluxing, cooling, esterifying, separating crude oil, deacidifying, adding flaky sodium hydroxide and medical stone, heating, centrifuging, filtering, separating oil, distilling, separating light component and heavy component, mixing heavy component with sulfuric acid, adjusting pH, adding granular medical stone, calcium oxide and clay and centrifuging.    USE - Preparation of oxidation-resistant biodiesel (claimed).    ADVANTAGE - The method enables preparation of oxidation-resistant biodiesel having excellent storage stability for long period of time, with high yield of 96%.    DETAILED DESCRIPTION - Preparation of oxidation-resistant biodiesel involves adding 100 g medical stone having particle size of 50-70 mesh to waste oil, stirring at 30-35 degrees C for 30 minutes, filtering using 100 mesh filter, obtaining filtrate, mixing 130 g anhydrous methanol and 2-3 g concentrated sulfuric acid having concentration of 98%, obtaining mixed liquid, adding mixed liquid to filtrate, obtaining raw oil, adding to furnace, heating to 70 degrees C, stirring at 70-80 degrees C, refluxing, separating methanol vapor, cooling, reacting for 2 hours, esterifying, discharging acidic water and glycerol mixture from furnace bottom, separating crude oil, deacidifying, adding 2-3 g flaky sodium hydroxide and 100 g medical stone, stirring at 30 degrees C and 60 rpm, heating at 60-70 degrees C for 20-50 minutes, centrifuging at 60 degrees C, filtering, separating oil, passing through heat exchanger, adding to distillation column, distilling, separating light component and heavy component, separating fatty acid methyl ester, mixing heavy component with 20-90 g sulfuric acid having concentration of 95% or more, adjusting pH value to 7-8, leaving still for 2 hours, adding 100 g granular medical stone, 30-50 g calcium oxide and 10-30 g clay, stirring for 20 minutes and centrifuging.