The trial was conducted to study effects of dietary tryptophan (Trp) level on growth performance, carcass traits, whole body nutrient retention and hypothalamic serotonin concentration in order to determine Trp requirements of Chinese color feathered chicks aged from 43 to 63 days. One thousand and six hundred Chinese color feathered chicks at 43 days of age were used. Five dietary treatments were compared in a 5×2 factorial design with five dietary Trp levels (0.11%, 0.14%, 0.17%, 0.20% and 0.23%) and two genders. The results indicated that supplementation of synthetic Trp increased growth performance, whole body protein retention and hypothalamic serotonin concentration in both female and male chicks, and improved carcass traits of male chicks. There were significant differences in growth performance, carcass traits and whole body protein retention between female and male chicks (P<0.05). Feed intake, feed utilization and whole body protein retention of male chicks were higher than those of female chicks, resulting in that male chicks grew faster and yielded more meat than female chicks Daily feed intake,breast muscle pecentage and abdominal fat percentage in response to dietary Trp concentrations is more sensitive for male chicks than for female chicks. Dietary total Trp concentration, digestible Trp concentration and total Trp/Lys ratio to gain 95% of the maximum ADG were 0.181%，0.162% and 20.1∶100 for male chicks, and 0.185%, 0.166% and 20.6∶100 for female chicks, respectively. Daily requirements of total Trp and digestible Trp to gain maximum ADG were 0.184 and 0.165 g/d for male chicks, and 0.169 and 0.152 g/d for female chicks. Dietary total Trp and digestible Trp concentration for both male and female chicks to gain maximum retention rate of body protein were 0.17% and 0.15%.