Abstract: The effects of simple controlled atmosphere(CA) on the contents of ethanol and organic acid and the activity of enzymes of "Brumal Jujube" during storage(0℃) were studied and the mechanism of ethanol fermentation was discussed. The results showed that CK caused the accumulations of ethanol and acetaldehyde and increased the activities of alcohol dehydrogenase(ADH) and pyruvate decarboxylase(PDC), but decreased the levels of organic acids, CA slightly increased the contents of ethanol and acetaldehyde and the activities of ADH and PDC, and kept higher levels of organic acids. During storage of ‘brumal jujube’, citric acid, succinic acid, fumaric acid, t-Aconitic acid concentrations decreased, malic acid concentration slightly increased, the concentration of pyruvate acid increased at early storage stages and decreased after the peak appeared. These changes of organic acid show that one of the main mechanisms of ethanol fermentation should be the reduction of these organic acids entering tricarboxylic acid(TCA) cycle and the increase of pyruvate acid during storage.