Provided are an anti-GITR antibody, an antigen-binding fragment thereof, and pharmaceutical use thereof. Further provided are a chimeric antibody and a humanized antibody containing a CDR of the anti-GITR antibody, a pharmaceutical composition containing the anti-GITR antibody and the antigen-binding fragment thereof, and use of the anti-GITR antibody in preparation of an anti-cancer drug. In particular, provided is a humanized anti-GITR antibody, and use in preparation of drugs for treating GITR-mediated diseases or disorders.