In this study, polysaccharides from the whole seed, cotyledon and hull of cowpea were extracted, isolated and purified, and their structural characteristics and antioxidant activities were compared. The results indicated that the basic chemical composition, monosaccharide composition and molecular mass distribution of the polysaccharides from different parts of cowpea, exhibited both similarities and differences. Structural characteristics of the polysaccharides from the whole seed (VUP) and cotyledon (VUCP) of Vigna unguiculata were similar. The polysaccharide from the hull (VUHP) was mainly composed of pectin, whose molecular mass distribution was more uniform. The antioxidant activity of VUHP was significantly stronger than that of VUP and VUCP, and the scavenging capacity of VUHP against 1,1-dipheny1-2-picryl-hydrazyl (DPPH) radical and 2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) cation radical was almost equal to that of vitamin C (VC). In summary, more attention should be paid to seed coat polysaccharides in the research and product development of polysaccharides from cowpea.