Abstract: To inspect the characteristic indexes and quality indexes of edible vegetable oils and catering waste oils, The characteristic indexes (refractive index, iodine value and short chain saturated fatty acid) was used to analyze the difference and identify catering waste oils. Principal component analysis (PCA) was applied to analyze the quality indexes (acid value, peroxide value, polar components, metal content and the content of trans fatty acids) and build mathematical evaluation model from five influence factor to distinguish catering waste oils by principal component scores. From results, there were significant difference between catering waste oils and vegetable oils in characteristic indexes. Each sample was evaluated by PCA mathematical evaluative model and the three samples' PCA scores of catering waste oils were higher than vegetable oils.Hence, catering waste oils quality was extremely debased, in totally subentry-combined evaluation could distinguish catering waste oils from others accurately.