Recombinant Anti-CD15 x Anti-CD64 Bispecific Antibody (Fab-Fv) is designed to be expressed as two polypeptide chains. The heavy chain Fd fragment and light chain of an anti-CD15 antibody are fused with the VL and VH domains of an anti-CD64 antibody respectively. It can form natural in vivo heterodimerization. This BsAb can retarget neutrophils to tumor cells. It is designed for the research of Leukemia therapy.