Abstract: To investigate the effects of alfalfa (Medicago sativa L.) meal on the growth performance, muscle quality and serum antioxidant index of grass carp (Ctenopharyngodon idella), five isonitrogenous and isolipidic diets (crude protein: 32.0%, crude fat: 4.12%) were formulated with 0 (control group), 5%, 10%, 15% and 20% alfalfa meal, respectively. Juvenile grass carp initial weight of (50.04±0.04) g were fed for 61 days. The results showed that: (1) Compared with the control group, the specific growth rate significantly decreased in the group with 20% alfalfa meal (P<0.05), and the feeding rate as well as the feed conversion ratio significantly increased in the group with 15% alfalfa meal (P<0.05). Except for the group with 5% alfalfa meal, the condition factor of grass carp significantly decreased (P<0.05). (2) Adding alfalfa meal significantly decreased the contents of muscle lactic acid and thiobarbituric acid values (P<0.05) and increased muscle water loss rate(P<0.05). The content of muscle hydroxyproline in the groups with 10% and 15% alfalfa meal were significantly higher than that in the control group (P<0.05). Except for the group with 20% alfalfa meal, adding alfalfa meal significantly increased the muscle adhesiveness (P<0.05). The muscle hardness significantly increased in the group with 10% alfalfa meal compared to the control group (P<0.05). (3) The serum CAT activity of grass carp in the group with 20% alfalfa meal was significantly higher than that in the control group (P<0.05). Compared with the control group, the serum GSH-PX activity of grass carp in the groups with 15% and 20% alfalfa meal significantly increased, and the content of MDA significantly decreased (P<0.05). In conclusions, adding less than 15% alfalfa meal could improve muscle quality and serum antioxidant capacity of grass carp. Therefore, the addition of alfalfa meal in grass carp feed should not exceed 15%.