Abstract: In order to study the in vitro and in vivo antibacterial effects of six Chinese herbal medicines, namely, Chinese gallnut, safflower, golden thread, garden burnet root, blackberry lily rhizome and milkvetch root on Aeromonas hydrophila, the sensitivity of Aeromonas hydrophila to the six herbal extracts was measured by Oxford cup drilling method and two-fold dilution method. The minimum inhibitory concentration（MIC） and minimum bactericidal concentration（MBC） of the herbal extracts were selected to effectively inhibit the bacteria. Healthy northeastern forest frogs were selected as the test subjects for the in vivo test, and the frogs were fed with the herbal mixture with good antibacterial effect for 56 d. Samples were taken on days 0, 14, 28, 42 and 56, and the immune indexes（acid phosphatase AKP, superoxide dismutase SOD and lysozyme LZM activities in serum, and the relative mRNA expression of interleukin-10 IL-10, interleukin-1β IL-1β, tumor necrosis factor-α TNF-α and interferon-γ IFN-γ genes in heart, spleen and lung tissues） were detected and the survival rate of Aeromonas hydrophila was determined. The results showed that among the six traditional Chinese medicines, the tested bacteria were moderately sensitive to Chinese gallnut, safflower and golden thread. The MIC of Chinese gallnut, safflower, golden thread, garden burnet root, blackberry lily rhizome and milkvetch root were 0.05, 0.10, 0.10, 0.20, 0.25, 0.20 g/mL, and MBC were 0.10, 0.15, 0.25, 0.25, 0.40, 0.40 g/mL, respectively. Chinese gallnut and safflower had strong antibacterial effect on the tested strains. Based on the results of bacteriostatic test in vitro, Chinese gallnut and safflower were divided into control group, Chinese gallnut group and safflower group. Compared with the control group, the activities of AKP, SOD and LZM in serum in gallnut group and safflower group were increased after feeding for 2 weeks. The expression levels of IL-10, IL-1β, TNF-α and IFN-γ genes in the heart, liver and spleen（except for the tissue of spleen in safflower group on days 42） were increased to different degrees. Chinese gallnut and safflower could effectively alleviate the invasion of Aeromonas hydrophila to northeastern forest frogs. It indicated that two Chinese herbs, Chinese gallnut and safflower, could inhibit Aeromonas hydrophila and immunomodulate northeastern forest frogs infected with aeromonas hydrophila.