Abstract: In the present study， Lingling red onion was taken as raw material. Different extraction solvents， solidliquid ratio， reaction time， reaction temperature and extraction times were employed to examine the influences on extraction yield of oleoresin. The chemical constituents were separated and identified by gas chromatographymass spectrometry （GCMS）， and the relative contents in percentage of compounds were determined by peak area normalization method. It was shown that the optimal extraction conditions were as follows: petroleum ether as extraction solvent， reaction temperature of 47 ℃， reaction time of 100 min， solidliquid ratio of 1∶8 and extraction times of twice. Under this conditions， the extraction rate could reach 0638 4% from 50 g Lingling red onion. A total of 18 volatile compounds were separated， and they accounted for 9781% of the total extractions， in which， sulfurcontaining compounds were 383%， acids were 2447%， ketones were 271%， alcohols were 1706%， esters were 1081% and aldehydes were 036%. The constituents included dimethyl disulfide， 1，3dithiane， hexanol， gadoleyl alcohol， 2methyl2pentanol， 3hydroxy2butanone， 5，7dimethylchromone3carboxaldehyde， palmitic acid， octadecadienoic acid， octadecenoate， dioctyl phthalate.

Key words: GCMS, Lingling red onion, onion oleoresin