Abstract: In recent years, the quality of edible oils has attracted wide attention because of food safety issues. One of the important reasons is the lack of effective detection techniques to detect illegal cooking oil. In this paper, the physical and chemical characteristics for quality assessment of edible oils are introduced, including water content, specific gravity, refractive index, saponification value, acid value, carbonyl value, peroxide value, iodine value, heavy metals, relative unsaturation values of fatty acids, cholesterol content, residue determination and oxidation product determination. The routine analytical techniques for detecting illegal cooking oil in edible oils are thin layer chromatography, spectrometry, water content determination, rapid detection method, chromatography,nuclear magnetic resonance, conductivity method, fungimycin method and gene identification method. However, there are some disadvantages to these techniques, such as poor specificity, low sensitivity and inaccuracy, which were applied to limited kinds of illegal cooking oil identification. Mass spectrometry is an important technique for the detection of illegal cooking oil, not only for the large number of structure information of samples it supplied but also for the high sensitivity and low detection limit itself. The portable mass spectrometer will also play a role and show the advantages when monitoring edible oil quality in the field.