object: To assess the mechanism of building an orthotopic murine bladder tumor model induced by silver nitrate, HCl, trypsin and ethanol. Methods: C57BL/6 mice were anesthetized and catheterized with 24G IV catheter, then divided into 5 groups (each n=6) after washing the bladders with phosphate-buffered saline (PBS); (1) Ethanol: 22% ethanol, incubated for 20min; (2) Trypsin: 0.2%trypsin, incubated for 30 min; (3) HCl: pretreated with 0.1mmol/L HCl for 15 s and 0.1mmol/L NaOH for 5 s after washing the bladders with PBS; (4) Silver nitrate: 0.15mol/L silver nitrate incubated for 10s; (5) Vehicle: normal saline. The mice were killed obtaining the bladder tissue after 1 and 24 hour. Pathological changes were observed by hematoxylin and eosin staining; microenvironment modification were assessed by electron microscope; mast cells were counted with toluidine blue staining; GAG layer were observed by periodic acid-schiff staining. Forty mice were intravesically pretreated with the former four factors, then incubated MB49 cells and determined the rate of tumor “take”. Results: In the model, partial umbrella cells slough, local muscular layer was incontinuous, and submucous layer appeared after 1 hour of pretreatment with trypsin and ethanol. The damage of muscular layer was more serious in HCl and silver nitrate groups. However, there was no statistically significant between experiment and control groups in inflammatory cells. Little edema mucosa and congestion, tight junction, and continuous muscular layer were observed in pretreatment by trypsin and ethanol 24 hours later. By contrast, thickness of muscular layer was inhomogeneity. Conclusion: Pretreatment method of silver nitrate and HCl caused serious damage in muscular layer, and more submucosal collagen and extracellular matrix exposed, compared with trypsin and alcohol. It maybe regard as the optimal choice in establishing orthotopic murine bladder tumor model.