Abstract： Objective To explore the effect of prevention of hemorrhagic cystitis (HC) after hematopoietic stem cell transplantation (HSCT) with hyperhydration, forced diuresis and alkalinizing plus infusion mesna. Methods 32 cases of patients receiving HSCT were included in this study. 2 cases of severe aplastic anemia (SAA) received total body irradiation (TBI)+cyclophosphamide(CTX)(TBI-CTX) regimen,and the remaining 30 patients were using the classic busulfan+CTX (BU+CTX) regimen. All patients were treated with mesna combined with hydration, forced diuresis and alkalization to prevent HC. Ganciclovir and acyclovir were used to prevent cytomegalovirus (CMV) and other viral infections and monitor CMV-IgM levels of the blood. Encourage patients to urinate every hour, testing urine pH value and the calculation of urine output, every 6 h review and testing of urine routine,central venous pressure (CVP), each of 8 h of serum electrolytes. Results Only 1 patient at 6 months after transplantation appeared delayed grade Ⅱ HC after hydration, alkalization, diuretic, hemostatic, anti-graft-versus-host disease (GVHD), and ganciclovir antiviral therapy. The HC patients cured at 35 d. The remaining patients did not suffer HC. Adverse effects such as acid-base balance disturbance did not appear clear. Conclusion Mesna joint hydration, forced diuresis and alkalization was effective and safe to prevent HC.