This current study was conducted to investigate the effects of dietary fulvic acid (FA) on performance, blood biochemical parameters and antioxidant indices in broilers. A total of eight hundred and forty 1-day-old Arbor Acres chicks were randomly divided into seven groups, and each group consisted of 6 replicates with 20 birds each (10 males and 10 females). The birds in each group were fed a corn-soybean meal diet supplemented with 0 (control), 0.012%, 0.024%, 0.048%, 0.120%, 0.240% FA and 50 mg/kg chlortetracycline (CTC), respectively. The feeding trial lasted for 42 days. The results showed as follows: 1) compared with CTC group, average daily feed intake of broilers aged 1 to 21 days was reduced by the supplementation of FA at 0.012% to 0.120% (P<0.05). Compared with the control group, at 1 to 21 days of age, the supplementation of 0.240% FA significantly increased average daily gain and reduced feed/gain (P<0.05), and the supplementation of 0.048% FA significantly decreased average daily feed intake and feed/gain (P<0.05); at 1 to 42 days of age, the supplementation of 0.024% and 0.240% FA significantly decreased feed/gain (P<0.05). 2) Compared with the control group, the supplementation of 0.048% FA significantly increased plasma superoxide dismutase activity and decreased malondialdehyde content of broilers aged 42 days (P<0.05), and the supplementation of 0.240% FA significantly plasma albumin content, total bilirubin content and alkaline phosphatase activity of broilers aged 21 days and lactate dehydrogenase activity of broilers aged 42 days compared with the control group (P<0.05). The results indicate that the supplementation of FA at 0.024% to 0.240% can improve performance of broilers, but the hepatic function of broilers might be adversely affected by the supplementation of 0.240% FA, and thus the supplemental level of FA in broiler diets should be less than 0.240%