To establish a method of gas chromatography-mass spectrometry to discriminate characteristic fatty acid from edible oil and evaluate the potential application to identify bio-waste oil from edible vegetable oil.Methods 22 mixtures of edible vegetable and bio-waste oils, 20 fried waste oils, 7 refined bio-waste oils, 9 original edible vegetable oil, 48 refined edible vegetable oil, 6 palm oils and 5 edible oils with flavor were prepared. After methyl esterification treatment, using UF-mFFAP capillary column gas chromatography column (30 m×0.25 mm, 0.25 μm), oil samples were analyzed by gas phase chromatography tandem-mass spectrometry for the detection of undecanoic acid methyl ester and 13 methyl tetradecanoic acid methyl ester. Results were under statistical tests according to sample categories to evaluate the effectiveness of waste oil identification using characteristic fatty acids. Results Dodecanoic acid could be used as the indicator for oils derived from animals, undecanoic acid could be used as the indicator for repeatedly fried oil. The combination of them could provide a sound basis for identification of edible vegetable oil and bio-waste oil.Conclusion The method for examining undecanoic acid methyl ester and dodecanoic acid methyl ester was of high sensitivity and good specificity, but false negative results can be obtained when vegetable oil is mixed with bio-waste oils. Other measures are necessary to improve the effectiveness to identify bio-waste oil from edible vegetable oil.