Abstract: Sphingan Ss was degraded by oxidative method, and a degradation product with weight-average molecular weight 10.3ku was obtained. The structure of degraded sphingan Ss was characterized by infrared spectrum and1H-NMR. The antioxidant capacity was investigated. The results showed that degradation product exhibited higher antioxidant activity than the sphingan Ss. The value of reducing power reached the maximum after a degradation time of 24 hours. The IC50 of scavenging hydroxyl free radical and superoxide anion was 8.32mg/mL and 12.13mg/mL, respectively.