The experiment was conducted to study the effects of dietary tryptophan levels on performance, antioxidant function and serum biochemical indices of yellow-feathered broiler breeders, and aimed to discuss a suitable supplemental level of tryptophan for the broiler breeders. Using a single factor and 4 levels arrangement of treatments design, a total of 360 yellow-feathered broiler breeders (28-week-old) were randomly allocated into 4 groups with 3 replicates in each group and 30 broiler breeders in each replicate. Broilers in control group were fed a basal diet which containing 0.16% tryptophan, and the others in experimental groups were fed the basal diet supplemented with 0.02%, 0.04% and 0.06% tryptophan, respectively. Pre-treatment period was 2 weeks and the experiment lasted for 8 weeks. The results showed as follows: 1) compared with the control group, each experimental group significantly increased the fertility rate, hatchability and birth rate (P<0.05), and the 0.18% tryptophan group was the highest among them. 2) Compared with the control group, the average body weight in the 0.18% tryptophan group increased 3.99% (P<0.05), the activity of glutathione peroxidase and the contents of total protein and albumin increased 12.58%, 13.40% and 4.02% (P<0.05), respectively. 3) The experimental groups had a trend of increasing the superoxide dismutase activity, total anti-oxidant capability and the content of reduced glutathione hormone, there also had a trend of reducing malondialdehyde and uric acid concentration in serum, however, there was no significant difference among those groups (P>0.05). 4) There was no significant difference among the groups in laying rate, average egg weight and feed/egg weight (P>0.05), but the average daily feed intake in experimental groups was significantly elevated compared with the control group (P<0.05). In conclusion, the optimal tryptophan level in corn-soybean meal diet of yellow-feathered broiler breeders is 0.18%.