Abstract: In order to improve the resistance and survival rate of juvenile grass carp (Ctenopharyngodon idellus ), the study investigated the effects of different doses ofHouttuynia cordata single preparations on the growth performance and physiological and biochemical indexes of juvenile grass carp after fed of different time, it could provide a theoretical guide forHouttuynia cordata as a feed additive to development and utilization. TheHouttuynia cordata powder added to the basic feed in proportion to the mass fraction of 1%, 2% and 3%. Grass carp individuals, the average weight of which was (10.83±0.57) g, fed of different concentrations of Houttuynia cordata single preparations. After fed of 30d, 60d and 90d, its growth index, muscle composition, lysozyme and SOD and other physiological and biochemical indexes were measured. Results showed: average weight and weight gain rate in group 2 increased significantly compared with those of the control group, and significantly higher than group 1 and group 3 at 30d, 60d and 90d(P <0.05). Every group could increase the lysozyme activity and NO content of grass carp, but only group 2 which fed 60d could significantly improve the lysozyme activity and NO content(P <0.05), but there was different reaction time between different organs. The SOD activity in every test group was much higher than those of the control group (P<0.05), and it gradually increased with the reaction time prolonged. The GOT and GPT activity in every test group were lower than those of the control group, and the GPT activity had significant difference between test groups and control group (P <0.05), so it showed some certain protective effect for liver cell. In a word, the optimum feeding time of Houttuynia cordata single Chinese herbal medicine feed additive was 30d to 60d and the optimum additive volume was 2%.