Abstract: The study aims to research the effects of adding puerarin in diets on non-specific immune function and hepatopancreas structure of grass carp (Ctenopharyngodon idellus). C. idellus with body weight of (4.52±0.22) g were fed with basal diet without (control group) or with 10, 50, 250, and 1250 mg/kg puerarin extract for 28 days. The results showed that the serum AKP activity significantly increased in the group with 10 mg/kg puerarin addition compared with that in control group (P<0.05), and SOD activity significantly increased in the groups with 10 and 50 mg/kg puerarin addition (P<0.05). However, LZM activity was not affected in all the tested groups. Hepatopancreas index and structure was not significantly different between tested groups and control group. After the feeding experiment, C. idellus were infected with Aeromonas hydrophila. Survival rates in the test groups all increased, and the increase was significant for the group with 10 mg/kg puerarin addition (immune protective rate of 73.33%, P<0.05). The results indicate that non-specific immune function can be improved by adding 10 mg/kg puerarin in diet, which cannot lead to hepatopancreas injury.