Abstract: Objective To investigate the effects of Butein on proliferation of BLS cells in human bladder transitional cell carcinoma(BTCC) in vitro and on transplantation tumor growth of bladder carcinoma in nude mice. Methods BLS cells were treated with Butein at various concentrations. Cell proliferation was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide（MTT）assay and clone formation assay, and cell cycle was detected by flow cytometry. Western blot was applied to measure phosphorylation of extra cellular signal regulated kinase（ERK1/2）, nuclear transcription factor kappa B (NF-κB) p65 expression, Cyclin D1 and COX2 expressions in downstream target genes of NF-κB. Transplanted tumors of bladder cancer in nude mice were constructed. Administration route was intraperitoneal injection. Volume and weight of transplanted tumors were measured. Results Butein inhibited cell growth and induced G2/M cell cycle arrest in bladder cancer cells. Phosphorylation of ERK1/2 and NF-κB p65 intranuclear expression were reduced（P<0.05）; Protein expressions of Cyclin D1 and COX2 were decreased（P<0.05）; Growth of transplant subcutaneous tumor in treatment group was obviously inhibited（P<0.05）. Conclusion Butein has anti-proliferation effect on human bladder cancer cells in vitro and in vivo possibly through suppressing ERK and NF-κB activation.