Abstract: An experiment was conducted to investigate the effect of dietary carnitine on growth performance, body composition and lipid metabolism enzymes of grass carp Ctenopharyngodon idella. The basal diet contained 31.36 % crude protein and 4.96 % crude fat. Five dietary treatments contained DL-carnitine concentrations of either 0(control group), 100, 200, 300 or 400 mg/kg diet. Dietary treatments were fed to apparent satiation third daily to triplicate groups of initially weighting （134.3±12.1） g per fish. Growth rate, feed conversion rate(FCR), crude fat and protein content of muscle and hepatopancreas, activities of intestine lipase, lipoprotein lipase(LPL), hepatic lipase (HL), total lipase and fatty acid synthase (FAS) were measured. At the end of the 8-week feeding trial, growth rate of fish fed with 200 mg/kg carnitine diet was increased by 5.70 % and FCR was decreased by 5.26 % compared with control group（P<0.05）, but no improvement was observed in other carnitine addition groups. hepatopancreas weight/ body weight, mesenteric lipid index and crude fat content of muscle and hepatopancreas were decreased（P< 0.05）, but length / height and condition factor K were not affected by adding carnitine of 200-400 mg/kg diet(P>0.05). Muscle protein content was the highest at 300 mg/kg　diet group. There were no significant difference in moisture and crude ash content of muscle, and protein content of hepatopancreas among all groups (P>0.05).Fish fed with 200,400 mg/kg carnitine diet, a lower concentration of serum cholesterol than the control group（P<0.05）. In the respect of lipid metabolism enzymes, the addition of 200 mg/kg carnitine increased intestine lipase activity, HL activity by 28.0%, 38.6%（P<0.05）, which were also increased by 41.41 %, 36.26 % by the addition of 400 mg/kg carnitine. At the same time, total lipase activity were increased by 10.66 %, and FAS activity decreased by 47.3 % by the addition of 400 mg/kg carnitine（P<0.05）. Results of above show that the addition of carnitine could improve the growth performance, decrease muscle and hepatopancreas fat content, promote lipid degradation. The proper dose of carnitine in grass carp diet was suggested to be 200 mg/kg.