Application of Chinese chestnut ellagic acid tannin in preparing bacteriostatic agent

The invention provides application of Chinese chestnut ellagic acid tannin in preparing a bacteriostatic agent. The preparation method of the Chinese chestnut ellagic acid tannin comprises the following steps: drying Chinese chestnut shells, chestnut flowers or chestnut leaves, processing into powder, adding into an ethanol water solution to obtain an ethanol water dispersion solution of chestnut shell, chestnut flower or chestnut leaf powder, carrying out ultrasonic extraction on the ethanol water dispersion solution, carrying out water bath reflux extraction, and carrying out freeze-drying on the concentrated filtrate to obtain the Chinese chestnut ellagic acid tannin. The invention detects that the Chinese chestnut ellagic acid tannin has high oxidation resistance and superhigh reducing power for the first time, and is especially suitable for removal of hydroxy free radicals, super oxygen free radicals, DPPH free radicals and the like and reduction of nitrites; and besides, the Chinese chestnut ellagic acid tannin has high antibacterial activity for Escherichia coli, Bacillus subtilis, Aspergillus oryzae, Aspergillus niger and other pathogenic microorganisms.