The goal of this phase 1/2 trial is to test the safety and efficacy of Venetoclax Plus Azacytidine Conditioning Regimen Allo-HSCT in treating patients with higher-risk MDS.

The investigators will evaluate 2 year overall survival(OS) after transplantation in patients with higher-risk MDS. Progression free survival (PFS), incidence of acute GVHD, non-relapse mortality (NRM), graft-versus-host disease (GVHD)-free relapse-free survival(GRFS), and incidence of chronic GVHD at 1 and 2 years after transplantation will be counted.

Inclusion Criteria:

• The patient should, in the investigator's opinion, be able to meet all clinical trial requirements.
• The patient is willing and able to adhere to the study visit schedule and other protocol requirements.
• The patient should be diagnosed with higher risk MDS according to the standard criteria of the World Health Organization (WHO).

Exclusion Criteria:

• Active or uncontrolled infections requiring systemic treatment within 14 days before enrollment.
• Any instability of systemic disease, including but not limited to severe cardiac, liver, kidney, or metabolic disease need therapy.