In this study, three acidic polysaccharides (APS-3a, APS-3b and APS-3c) were obtained from Angelica sinensis (Oliv.) Diels. They displayed different structural features and anti-tumor activities. APS-3b and APS-3c significantly inhibited the growth of S180 tumors and increased the life spans of S180 tumor-bearing mice, whereas APS-3a had no significant effect. Further experiments showed that APS-3b and APS-3c could cause a concentration-dependent proliferation of the splenocytes, up-regulate IFN-gamma, IL-2 and IL-6 mRNA expressions in splenocytes and stimulate the productions of NO and TNF-alpha in peritoneal macrophages. Taken together, the three acidic polysaccharides displayed different anti-tumor activities which were associated with their different structural characteristics.