Polysaccharide is used for adjuvant immunotherapy of malignant diseases.We studied the potential applicability of Selenium polysaccharide (SePS) from Spirulina platensis for improving immune function using an experimental model of murine lymphoma,compared with polysaccharide (PS) in Spirulina platensis. SePS and PS have no effect on thymus index;spleen cell proliferation was heightened by high concentrations of SePS and PS;synergism of SePS,PS with ConA is significant.SePS treatment enhance the ability of natural killer cell in mice spleen to kill target cell of YAC 1;conclusively,SePS treatment is more significant in the improvement of immuofunction than that of PS.