Provided is an antibody drug conjugate, specifically comprising a therapeutic antibody moiety, an intermediate linker moiety and a cytotoxic drug moiety which are linked. The therapeutic antibody moiety is an antibody against an HER2 target. The cytotoxic drug moiety is a camptothecin topoisomerase I inhibitor. The cytotoxic drug moiety or the linker-cytotoxic drug moiety is modified by means of deuterium substitution. The antibody drug conjugate can be used for the prevention or treatment of cancers.