Provided is a tetravalent, homodimer-type bispecific antibody molecule that targets both immune effector cell antigen CD3 and tumor-related antigen CD19. The bispecific antibody molecule comprises first and second single-chain Fv and Fc fragments in sequence from the N-terminus to the C-terminus, wherein the first single-chain Fv can specifically bind to CD19, the second single-chain Fv can specifically bind to CD3, the first and second single-chains Fv are connected by means of a linker peptide, the second single-chain Fv and Fc fragments are directly connected to each other or connected by means of a linker peptide; and the Fc fragment does not have effector functions such as CDC, ADCC, and ADCP. The bispecific antibody can significantly inhibit or kill tumor cells, and has toxic and side effects that may be caused by excessive activation of effector cells; in addition, such bispecific antibody is of homodimer type, without the problem of heavy chain and light chain mismatch; the purification step is simple and efficient, the expression is high, and the physical and chemical properties as well as in vivo stability of the antibody are significantly improved.