Objectives To investigate the effects of the membrane toxin 12 (MT-12) from Naja naja atra venom on human bladder cancer cell EJ-m3 and study its mechanisms. Methods Using a specially constructed in vitro invasion chamber cells that penetrate the Matrigel were selected and cultured to establish offspring cell lines;The growth inhibition rates of EJ-m3 cell were investigated by MTT method with various concentration MT-12.chemokine receptor CXCR4 expressions were detected by flow cytometry after 24 hours with various concentration MT -12. Results Acquire offspring cell lines nime EJ-m3 cell from bladder cancer cell EJ by selected again and a-gain. MT-12 effectively inhibited the growth of EJ-m3 cell,which depended on concentration of the drug. The IC50 after 72 hours with MT-12 on EJ-m3 ceil were 0.66ug/mL, flow cytometry results indicated that the expres-sion of CXCR4 gradually decreased with the increase of MT-12 dose(0. 125-0.5ug/mL group, p =0. 020).Conclusions MT-12 could significantly inhibit the growth of bladder cancer cells, The strong expression of CXCR4 might be one of its action mechanisms. MT-12 are largely potential anticancer drug for bladder carcinoma.