Abstract: Experiments using PEG2000/(NH₄)₂SO₄ aqueous two-phase system extraction chicken endogenous protease,combined with electronic nose and GC-MS detection of protease before and after the meat flavor changes. The results showed that when the mass fraction of PEG2000 32%,mass fraction of(NH₄)₂SO₄ 32%,pH6.5,the extraction rate of chicken protease reached 83.48%. With this condition extraction of protease treatment of chicken.The use of electronic nose could be very good to distinguish between the changes in the volatile matter in the chicken samples before and after treatment. 66 kinds of volatile components were detected by GC-MS,mainly including aldehydes,hydrocarbons,aromatics,sulfur compounds,organic acids,alcohols and esters volatile substances,the relative contents of aldehydes,aromatics and sulfur compounds in the blank group were significantly higher than those in the blank group. To sum up,the result shows that chicken proteinase could greatly increase chicken flavor.