The discrimination between animal oil and vegetable oil was analyzed by gas chromatography-mass spectroscopy(GC-MS) using esterifying oils under the presence of KOH.Six main fatty acids(myristic acid,palmitoleic acid,palmitic acid,linoleic acid,oleinic acid and stearic acid) were determined.It was found that animal oil and vegetable oil not only has a difference in components and relative content,but also has a difference in unsaturation.According to all of these differences,animal oil can be discriminated from vegetable oil.