Provided by the invention is an antibody or an antigen-binding fragment thereof, which binds to a CD38 protein at a KD value below 1×10-9M. The antibody or an antigen-binding fragment thereof has strong specific recognition and binding capabilities for CD38 protein, and may kill CD38+ cells by means of antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC) and/or apoptosis. Further provided by the present invention is an application of the antibody or antigen-binding fragment thereof in preventing and treating tumors.