The polysaccharide LBPP was extracted and isolated from the pollen of Brassica napus L., and the anti-tumor activity was evaluated on Sarcoma 180-bearing mice and B16 melanoma-bearing mice through transplantable animal tumor. Mice were treated with three doses of the polysaccharide LBPP (50, 100 and 200 mg/kg body weight) for 10 days. Tumor weight, relative spleen and thymus weight, lymphocyte proliferation, natural killer cell activity, delayed type hypersensitivity (DTH), phagocytic function of monocyte, serum hemolysis antibody and peripheral blood of tumor-bearing mice were studied. At the doses of 100 and 200 mg/kg, a significant decrease (P<0.01) in tumor formation, a significant increase (P<0.05) in relative spleen and thymus weight, natural killer cell activity, phagocytic function of monocyte, lymphocyte proliferation, and serum hemolysis antibody, and a significant improvement of peripheral blood abnormality (P<0.05) and anemia (P<0.01) were observed. Results of these studies demonstrated that the polysaccharide LBPP had anti-tumor activity, which was mediated by immunomodulation and leukogenic and antianemic actions.