A long-term feeding study was conducted to determine the effects of dietary β-glucan on the growth performance, nonspecific immunity and resistance to Aeromonas hydrophila challenge of carp（Cyprinus carpio）. Fish were fed three diets with 0, 0.15% and 0.50% of β-glucan, respectively. The trial lasted for 60 days. The results showed that neither weight gain rate nor feed conversion ratio of the carp fed diets with different doses of β-glucan was significantly different from that of the control group. Hepatopancreas lysozyme and acid phosphatase activities decreased significantly in β-glucan groups compared with the control group, but myeloperoxidase activities in different tissues of carp were not influenced by dietary β-glucan. The survival rates of β-glucan groups were lower than that of the control group after injected Aeromonas. hydrophila. In conclusion, β-glucan in the long-term feeding regime exerted no effect on the growth performance, but could reduce the non-specific immune function and disease resistance of carp.