Abstract: Immune checkpoint inhibitors (ICIs), as a new immunotherapy strategy, avoid immune escape and restore the human body's immune response by blocking the binding of programmed death-1 (PD-1) and its ligand PD-L1 to enhance the anti-tumor effect of the body's immune system. ICIs have become one of the most popular fields of anti-tumor therapy. PD-1 inhibitors have shown good efficacy in the treatment of more and more solid tumors. However, the application experience in hematological malignancies is still relatively limited. This article reviews the clinical studies on PD-1 inhibitors in hematologic malignancies and discusses its clinical application prospect.