A study was conducted to investigate the effects of supplemental VC in practical diet on growth,meat quality and non-specific immunity of adult grass carp(Ctenopharyngodon idellus). Three practical diets added with L-ascorbyl-2-phosphate as VC 0 (control group), 100 or 200 mg /kg respectively,were fed to triplicate groups of adult grass carp with body weight of (614.9 ± 60.5) g for 60 days.Resultsshowed that the growth rate of grass carp was significantly increased,whereas feed conversion ratio was decreased by supplemental VC 100 or 200 mg /kg in diet (P<0.05). Collagen content of muscle,muscle fiber diameter and liver VC concentration increased with the increase of VC supplement (P<0.05). The activity of serum SOD(superoxide dismutase) was significantly higher than that of control group when supplemental VC was 100 or 200mg /kg diet,and serum AKP (alkaline phosphatase) activity significantly increased when supplemental VC was 200mg /kg diet (P<0.05). There was no effect of supplemental VC in diets on the activity of LSZ(lysozyme) (P>0.05). It is suggested that supplemental VC in diets could improve growth performance,meat quality and serum non-specific immunity indices of grass carp.For adult grass carp,the VC supplement in diet was estimated to be 100 mg · kg-1 based on growth performance.