The aromatic substances illegally added in edible vegetable oil were detected by headspace solid-phase microextraction - gas chromatography-mass spectrometric (HS-SPME-GC-MS). Different brand of peanut oil, sunflower oil, sesame oil and their essences were separated and identified by HS-SPME-GC-MS, the spectra were obtained. The result showed that the main volatile substances in peanut oil, sunflower oil and sesame oil were aldehydes and pyrazine, which account for about 70% of total volatile matter, respectively; that in their essences were esters and phenols, which account for about 60%,70% and 75%, respectively. The result showed that since the fingerprints of GC/MS chroamtograms of vegetable oil were of great differences from those of corresponding essences, HS-SPME-GC-MS can be an effective analytical method to detect the illegal addition.