BK virus（BKV）associated hemorrhagic cystitis is one of the most common complications after hematopoietic stem cell transplantation（HSCT）, which can increase the suffering, become time consuming and even life threatening. However, BKV infection has not attracted enough attention in clinical practice. Accurate BKV monitoring and effective clinical treatments are still in urgent need. In recent years, BKV-DNA monitoring has shown a significant clinical value in BKV-associated hemorrhagic cystitis after HSCT. As for clinical treatments, traditional antivirus agent cidofovir is still to show promising effects, in the meantime, the virus-specific lymphocytes and other new therapies are continuously appearing. Here, the most recent advances on pathogenesis, treatment, virus monstoring and so on for BKV associated hemorrhagic cystitis after HSCT are reviwed.