Three polysaccharides (SAP30, SAP60 and SAP80) were separated from the body of Edwardsia sipunculoides by tissue homogenate and papain hydrolysis. Total soluble sugar contents, monosaccharide compositions, antioxidant and antitumor activities in vitro of those polysaccharides were investigated, respectively. Results showed that the total soluble sugar contents of SAP composed of Man, GlcN, Rha, GalN, GlcUA, Glc, Gal, Xyl and Fuc were more than 85% estimated by the phenol-sulfuric acid assay. In addition, SAP had potential antioxidant and antitumor activities. SAP30 has the most significant antitumor effect. This study suggested that SAP could be a potential natural antioxidants and antitumor agents.