A bispecific antibody that the Fab of anti-CD123 antibody variable domain is fused to the Fc-knob domain with a hinge region and the same as the scFv of anti-CD3 to the Fc-hole domain, or vice versa. This BsAb can retarget T cells to tumor cells. It is designed for the research of Acute myelogenous leukemia (AML); Chronic myelogenous leukemia (CML); Plasmacytoid leukemia therapy.