Provided in the present application is a humanized and multifunctional CD3 antibody; a heavy chain variable region of the CD3 antibody comprised herein contains the amino acid sequence of any one of SEQ ID NOs: 1-3 or a variant sequence thereof; and a light chain variable region thereof contains the amino acid sequence of any one of SEQ ID NOs: 26-28 or a variant sequence thereof. Further provided in the present application is a multifunctional antibody comprising (a) a light chain-heavy chain pair that has specificity for tumor cells or microorganisms; and (b) a fusion peptide that comprises a single-chain variable fragment and an Fc fragment having a CH2 domain and/or a CH3 domain, the fusion peptide having specificity for immune cells. The antibodies provided in the present application have improved biological activity, thermal stability and/or acid resistance.