Abstract: Objective To explore the effects of ganoderma lucidum polysaccharide(GLP) in chemotherapy on urinary bladder cancer and the mechanism of its role in immune escape. Methods The spleen indexes were examined in T24 bearing mice after receiving treatment with GLP and cisplatin; flow cytometry was used to test the proportion of lymphocyte subsets in spleen and blood; the serum levels of IL-10, VEGF, TGF-β, IL-2 and TNF-α were detected by ELISA. And the expression of IL-2 and TNF-α in spleen were assayed by reverse transcriptase PCR (RT-PCR) and Western blot. Results The spleen index was significantly increased after treated with GLP(200mg/kg) for 18d(P<0.001). The mice receiving cisplatin plus GLP achieved higher proportion of lymphocyte subsets(CD4, CD8, NK and DC) and lower amount of myeloid-derived suppressor cell (MDSC) in either spleen or blood, compared with those received cisplatin alone. ELISA analysis showed that GLP could obviously increase the productions of immune-related factors (IL-10, VEGF, TGF-β, IL-2 and TNF-α) in peripheral blood (P<0.05). RT-PCR and Western blot also confirmed that GLP obviously promoted the expression of IL-2 and TNF-α in spleen during chemotherapy. Conclusion GLP could enhance the immunity of mice and the anti-tumor effect of chemotherapy by improving the spleen index, increasing the contents of lymphocytes and immune factors in spleen and peripheral blood and enhancing the IL-2 and TNF-α expression in splenocytes. The mechanism may be associated with decreasing immune escape function of GLP.