Abstract: In order to explore the growth performance, organic health and nutritional metabolism level of Ctenopharyngodon idella, a fed herbivorous fish-grass carp, with high dietary carbohydrates, we divided 1 800 individuals of (132.01±16.43) g into normal carbohydrate diet group (Control group) and high carbohydrate diet group (Group H), feeding them with 15% and 45% level carbohydrate diets for 140 d. Each group included three replications and each replication included 300 individuals. The results show that compared with the control group, the body mass of Group H was higher significantly on 60^th, 80^th and 140^th day (P<0.05). The visceral body ratio, mesenteric fat coefficient, villus height and hepatic glycogen content of Group H increased significantly on 140^th day, and damage was observed in liver and intestinal tract. The expression of glucose kinase gene (gk), pyruvate kinase gene (pk), glycogen synthase 2 gene (gys2) and fatty acid synthetase gene (fas) showed a decreasing trend in Group H along with time, while phosphoenolpyruvate carboxykinase gene (pepck) and glucose-6-phosphatase gene (g6pase) showed an increasing trend. The expressions of gys2, fas, pepck and g6pase had the same trend in Group L as that in Group H, while no significant variation trend was observed in gk and pk gene at each time. Compared with the control group, the expression of pk was significantly lower, while those of g6pase, pepck and fas were significantly higher in Group H. In conclusion, 40% level dietary carbohydrate can improve the weight gain rate of grass carp, but high dietary carbohydrates have a negative impact on physiological indicators and significantly affect glucose metabolism at molecular level.