Jian carps were developed by comprehensive breeding technique as a new variety with fast growth, efficient feed conversion, strong disease resistance, high market value, and excellent hereditary properties, and are considered a commercially important teleost for inland culture in China. The expriment was conducted to determine the effects of dietary hight levels vitamin A on growth performance, feed utilization and immune responses in juvenile Cyprinus carpio var. jian. Prior to the formulation of diets, vitamin A contents of ingredients were analyzed fluorimetrically and vitamin A was found to be absent in the fishmeal, rice protein meal, а- starch, the soya oil. Five diets with increasing dietary vitamin A concentration (3 969 IU·kg-1,23 816 IU·kg-1,39 693 IU·kg-1,99 233 IU·kg-1 and 158 773 IU·kg-1, respectively) were randomly fed to triplicate groups of 40 fish (initial mean weight 11.37 ± 0.55g) each for 70 days. Juvenile Jian carps were obtained from a local commercial farm and stocked in the glass tanks for 2 weeks prior to the trial. At the beginning of the experiment, all fish in good health and condition were stocked in each aquarium (80 × 55 × 30 cm3).All dry ingredients were finely ground, carefully weighed and mixed thoroughly in a Hobart mixer. Vitamin A was pre- added in an oil mixer. The wet mash of even consistency was cold- extruded through a pelletizer with a 2- mm diameter die. The dry pellets were placed in covered plastic bags and stored frozen at -20℃ until fed. Each replicate was provided with flow – through tap water (2 liter min-1), constant aeration and cleaned as needed. Initial daily ration was 3 – 4% of the body weight and adjusted according to feeding response. Based on visual observation, fish were fed by hand to apparent satiety twice per day in two equal portions at 0900 and 1500 h over a 10- minute period. Water quality parameters were monitored twice weekly. Water temperature was maintained at 21℃; dissolved oxygen ≥ 5.0 mg l-1; total ammonia- nitrogen 0.025 - 0.042 mg l-1. At the termination of the growth trial, ten fish with similar body weight were obtained from every tank and moved to the same tank, acclimated to the culture condition for five days prior to infection and maintained at 25℃ and kept another 15- days challenge trial. The challenge bacterium, Aeromonas hydrophila, stored at -70℃ until use. The control group (non- infected group) was injected i.p. with 0.5 ml 0.9% NaCl fish-1. The fish were observed daily and moribund fish were recorded from the aquaria for the subsequent 15 days. A vaccination trial was conducted following the 70- day growth trial. At the termination of the growth trial, 12 disease – free fish with similar body weight in each tank were obtained pooled by diet and cultured in one tank maintained at 25℃ during the following 24- day vaccination experiment. Fish were acclimated to the vaccination trial culture condition for five days prior to immunization. Daily feeding and management were the same as in the growth trial. The results showed: weight gain, protein retention rate(PRR), hepatopancrease weight, intestinal folds hight, spleen index,blood hematocyte and leukocyte counts, serum lysozyme activity and serum antibody level at 17d and 24d after vaccination against Aeromonas hydrophila decreasing significantly in fish fed dietary hypervitaminosis vitamin A (158 773 IU·kg-1) (P<0.05), feed conversion efficiency, vitamin A contend in hepatopancrease increasing significantly were determined in fish feeding hypervitaminosis vitamin A (P<0.05), but were not significant differences in survival rate, feed intake, head kidney weight, post kidneyindex and serum antibody level at 0d and 10d after vaccination against Aeromonas hydrophila between five groups (P>0.05). Based on growth performance, feed utilization and immune response, it was toxic to juvenile Jian carps when diet contained vitamin A 158 773 IU·kg-1.