Abstract: The aim of the present study was to evaluate the effects of dietary supplementation of algal polysaccharide on antioxidant capacity of broilers. A total of 180 one-day-old healthy broiler chicks were chosen and equally divided into control group, antibiotic supplementation group and algal polysaccharide supplementation group. There were 3 repeats for each group and20 chicks for each repeat. At the 21 thand 42thdays of age, the serum total antioxidant capacity and the serum content of superoxide dismutase, glutathione peroxidase and malondialdehyde of broilers in different groups were determined and statistically evaluated.The results revealed that the antioxidant capacity of broilers in algal polysaccharide supplementation group was obviously increased which was significantly higher than that of control group（P〈 0.05）. The surviving rate of broilers whose diet supplemented with algal polysaccharide was significantly increased.