The invention relates to an anti-human PD1 monoclonal antibody and a use thereof as well as provides an encoded nucleic acid molecule, an expression vector and a host cell of the antibody and a methodfor expressing the antibody. The invention also provides an antibody immune coupling conjugate, a bi-specific molecule, a chimeric antigen receptor and a drug composition of the antibody and uses ofthe antibody immune coupling conjugate, the bi-specific molecule, the chimeric antigen receptor and the drug composition. Compared with the prior art, the use can specifically recognize a human PD1 monoclonal antibody, the affinity of the antibody binding with human PD1 is stronger than the existing anti-human PD1 monoclonal antibody, and a sequence of the antibody is novel.