The study aims to evaluate the effects of dietary emodin, high-dose vitamin C (Vc) and their combination on the disease resistance of Aeromonas hydrophila infection. One thousand and two hundred healthy fish with initial body weight of (133.44±2.11) g were selected and randomly divided into four groups: one was the control group fed with basal diet (containing Vc 50.3 mg/kg, with the L-ascorbyl-2-polyphosphate as Vc source); the other three were the treatment groupsnted with emodin 60 mg /kg, Vc 700 mg/kg, and the combination of emodin 60 mg/kg + Vc 700 mg/kg, A. hydrophilathe biochemical parameters of serum and liver, the mRNA levels of two heat shock protein 70s (HSP70s) in liver infection were determined. Another ten fish taken from each tank were challenged with using the same method as above, and the cumulative mortality of each group was counted at different time of post-infection. The results showed that before infection, compared with the control group, serum total protein (TP), lysozyme (LSZ) and alkaline phosphatase (AKP) levels, liver superoxide dismutase (SOD) activity and expression level of inducible HSP70 mRNA significantly increased , while serum cortisol (COR), triglyceride (TG) and liver malondialdehyde (MDA) contents decreased ( <0.05) in emodin and Vc groups; the liver catalase (CAT) activity also significantly increased in <0.05). Although the serum TP, LSZ and liver HSP70 mRNA levels significantly increased , and the liver malondialdehyde (MDA) level was also significantly reduced (<0.05), no synergism was shown.After infection, compared with the control group, the serum TP, LSZ, AKP levels, liver SOD, CAT activities, and the expression levels of HSC70 and HSP70 mRNA increased in varying degrees, while the serum COR, glucose (GLU), combination group, although these parameters had similar changing trend as the above ones, most of them were not significant different with the control (> 0.05), and also did not . Statistic data also showed that after infection with A. hydrophi1asignificantly lower than the control group was not significant (> 0.05). could improve non-specific immunity of fish, capacity, and two HSP70s mRNA expression However, the combination of emodin and high-dose Vc showed no better effect, and the mechanism of their interaction