As one of the redox enzymes,some aging aldehydes are produced by lipoxygenase in the oxidation reaction,which may affect the flavor stability of beer. Herein,the original measurement of lipoxygenase was optimized and 27 different kinds of barley were researched. The result showed that the optimal reaction temperature was 25℃and the pH of optimal buffer solution in reaction system was 8. 0. The addition of extracted crude enzyme was 50μL and the concentration of substrates was 5mmol / L. Besides,the repeatability and reproducibility were respectively less than 5% and 5. 26%. The significant difference of lipoxygenase was found in the different fields,years and genetic types of barley.