A water-soluble low molecular weight polysaccharide (SCPP11) was extracted and purified using DEAEcellulose and Sephadex G-100 column from Schisandra chinensis (Turcz.) Baill. Its in vivo and in vitro antitumor and immunomodulatory activity were investigated. The results showed that SCPP11 with a molecular weight of 3.4 103 Da exhibited indirect cyctotoxic activity against tumor cells in vitro, but could significantly inhibit the growth of Heps cells in vivo at dose of 50 mg/kg, and its inhibition rate is higherthan that in the positive group. Moreover, SCPP11 could ameliorate the hematological and biochemical parameters to almost normal and no significant changes in organ weight, and could increase the bodyweight. In addition, SCPP11 (at 50 mg/kg) could also increased in thymus indexes as well as IL-2 and TNF-a levels in serum in vivo and significantly enhance the phagocytosis activity and the productions of NO of RAW264.7 in vitro. The results indicated that antitumor properties of SCPP11 might be achieved by improving immune response. It could be explored as a potential adjuvant against cancer used in the health food and pharmaceutical therapy.