Abstract: A Claudin18.2 humanized antibody and application thereof. The antibody contains a chain variable region (CDR) sequence selected from at least one of the following or an amino acid sequence having at least 90% identity therewith: light chain CDR sequences: SEQ ID NOs: 1-3 and 7-9; and heavy chain CDR sequences: SEQ ID NOs: 4-6 and 10-12; The antibody or an antigen-binding fragment thereof have humanized modification. The humanized antibody can specifically target and bind Claudin18.2, has the same in vitro activity as a human-mouse chimeric anti-Claudin18.2 monoclonal antibody, meets the requirements of druggability, and has significantly prolonged in vivo half-life.