Recombinant Anti-Csl x Anti-CD3 Bispecific Antibody (IgG-Fv) is formed by an Immunoglobulin G (IgG) and a fragment variable Fv region, in which the Fc of IgG is engineered by KIH. The Fv region of an anti-Csl antibody variable domain is fused to the C terminal of an IgG of anti-CD3 antibody, or vice versa. The format retains desired characteristics of intact antibodies. This BsAb can retarget T cells to tumor cells. It is designed for the research of Breast cancer; Glioma cancaer; Glioblastoma; Multiple myeloma (MM); Leukemia therapy.