PD-1, a genetically programmed death receptor 1, is an important immunosuppressive molecule of the immunoglobulin superfamily. Immunomodulation targeting PD-1 has a role in antitumor (can regulate its occurrence, development and growth), anti-infection (can kill pathogenic microorganisms through immunity), anti-autoimmune diseases (can control immunity through target stimulation) and organ transplant survival. Its ligand PD-L1 has corresponding antibodies that can play the same role. the combination of PD-1 and PD-L1 initiates programmed death of T cells, allowing tumor cells to gain immune escape and tumor cell proliferation to occur.