Abstract: The effective components of Chinese Herbal Compounds Gallnut for fishery antimicrobial agent are separated and identified by thin-layer chromatography and column chromatography.Through antibacterial test and joint drug test of several aquatic animal pathogens in vitro,the antibacterial strength of active ingredients of the compound and the inter-relationship between the drug components are determined.The mechanism of Chinese Herbal Compounds Gallnut is supplied with the theoretical basis and the quality control is provided for its reference.The lamina is made with silica gel GF254 and the developing agent is spread with benzene:ethanol:formic acid(7:3:1).Moreover,it is colorized with NH3-FeCl3 and the result should be observed under sunlight.The monomer is isolated through dry silicon column loaded and it is eluted with benzene:ethanol:formic acid(7:3:1).The active ingredients of Chinese Herbal Compounds Gallnut are identified for physical and chemical properties and by thin-layer chromatography analysis.The results shows that the effective components of Chinese Herbal Compounds Gallnut are tannins,gallic acid,quercetin,baicalin,aloe emodin,emodin,1,8-2 hydroxy anthraquinone.The most content monomer is gallic acid by UV spectrophotometry for 10.47%.The antibacterial action for Aeromonas sobria,A.caviae,Edwrdsieda torda and flavobacterium columnare is tested.Aeromonas sobria selected as the object and the main active ingredients for two matched,antibacterial action in vitro is tested.Antibacterial order of the active ingredients is as follows:gallic acid anthraquinone baicalin quercetin tannide.There is synergy between gallic acid and anthraquinone,there is cumulative effect between gallic acid and baicalin,gallic acid and quercetin,anthraquinone and baicalin,respectively.