The influence of different concentrations of Sb(Ⅲ) and Sb(Ⅴ) on the growth rate, chlorophyll a content, antioxidant enzyme activities and superficial structure of Scenedesmus obliquus were investigated. The results showed that the alage respond more rapidly to Sb(Ⅲ) under the experimental group of high concentration of Sb(Ⅲ) and Sb(V). The content of chlorophyll a decreased with increasing concentrations of Sb(Ⅲ) and Sb(V), and is more sensitive to the change of Sb(Ⅲ). Under the 800 μmol/L of Sb(Ⅲ) and Sb(Ⅴ) stress, the content of MDA and activity of SOD in the algal changed significantly in 7^th-8^th day and 6^th-7^th day, respectively. In contrast, the activity of CAT change more rapidly under Sb stress, and increased rapidly in 4^th-5^th day. The high concentration of Sb(Ⅲ) and Sb(V) significantly affect the biomass, chlorophyll a content and superficial structure of alage cell. This stress effect was closely related with both Sb(Ⅲ) and Sb(Ⅴ) concentration and treatment time; S. obliquus can alleviate this inhibition by increasing its antioxidant enzyme system.