This study is a single arm, open label Phase Ib clinical trial, consisting of two parts: the first part is a safety introduction trial, and the second part is a dose escalation trial. In the first part, the tolerability, safety, PK characteristics, PD characteristics, and preliminary efficacy of VIC-1911 tablets in combination with PTCy and sirolimus will be explored. The first part will conduct safety introduction tests at the same dose as those already tested abroad to determine the dosage required for VIC-1911 tablets to meet safety and effective biological activity. The dose limiting toxicity (DLT) in Phase I study will be evaluated from the first administration of VIC-1911 tablets to 28 days after administration. On this basis, the second part of the experiment will be conducted to further explore the effectiveness and safety of VIC-1911 tablets combined with PTCy and sirolimus under RP2D for preventing GVHD in haplo HSCT patients after myeloablative pretreatment