Abstract: In this paper，the changes of indigenous microorganisms，sugars，organic acids，color， polyphenolics，and antioxidant activity were investigated during natural fermentation（sealed by water）of citrus peels. Results showed that during natural fermentation of citrus peels，lactic acid bacteria and yeasts were dominant strains，the texture of citrus peel could be retained well，and its color（green）gradually turned into dark brown. The soluble bond phenolics were the dominant phenol，and the changes of phenolics and antioxidant activity were positively related. Moreover，discontinuously opening the water seal for ventilation could accelerate the brown of citrus peel color during fermentation，but had no significant effect on the natural microbial flora，sugars，organic acids，polyphenolics and antioxidant activity.