In higher plant,hydroperoxide lyase(HPL) catalyzed the cleavage of hydroperoxide,which converted from linoleic or linolenc acid by LOX,to give C6 volatile aldehyes together with ω–oxoacids.These volatile aldehydes are important contributors to the distinctive scent of fresh fruits and vegetables,C6 aldehydes are an important flavor additive in food industry and chemical industry.Based on the single-factor tests,combination of the extraction parameters was optimized by using four-factor-three-level orthogonal test.The optimum conditions were determined as follows: speed 12 000r/min,pH =8.0,contained 1mmol / L cysteine and 0.3%(m / v) PVP as a buffer.Under that condition,the total enzyme activity of HPL was high.We also explored the effect of the vacuum the extraction of HPL and found that if the HPL was extracted under the condition of complete oxygen removal,its total enzyme activity would be significantly improved.