Abstract: Crisp grass carp is a common name for Ctenopharyngodon idellus that is fed with faba bean (Vicia faba) for 100 days and thus has improved flesh quality, flexibility and mastication properties compared to grass carp fed with regular formula. To better understand the changes in the physiology of crisp grass carp, we explored and compared the antioxidative status and immune functions of crisp grass carp (grass carp fed with faba bean, FB) and common grass carp (grass carp fed with formula feed, FF). Both the FB and FF groups were reared for 30 days, 60 days and 100 days before sampling. The results showed that FB markedly affected the SOD activity in the liver, and T-AOC and MDA in the serum. However, it had little impact on T-AOC and MDA in the liver, GSH in the liver, and the SOD activity in the serum. Fish fed with FB possessed higher antioxidative capability than those fed with FF when tested on the 30th and the 60th day; however on the 100th day the antioxidative capabilities of the two groups were similar. On the 100th day WBC and RBC of the FB group were significantly higher than those of the FF group. On the 30th and the 100th day levels of TP, ALB and GLB in the serum were significantly decreased by feeding with FB compared to the FF group. In the contrast, there was no difference in the serum TP, ALB and GLB between the two groups on the 60th day. The spleen index and the transcription of some immunity-related genes in the spleen could also be altered by diet. On the 100th day, the transcription of IL-1, MHC Ⅱ, IFN-1 and TNF- in the spleen of the FB group was significantly higher than that of the FF group. These results indicated that antioxidative capability of grass carp could be initially enhanced by feeding with faba bean, followed by a decrease to the level of grass carp fed with formula feed. The immune functions of grass carp could also be changed by feeding with faba bean.