Recombinant Anti-FGFR1 x Anti-KLB Bispecific Antibody (Fab-Fv) is designed to be expressed as two polypeptide chains. The heavy chain Fd fragment and light chain of an anti-FGFR1 antibody are fused with the VL and VH domains of an anti-KLB antibody respectively. It can form natural in vivo heterodimerization. This BsAb can bind two factors simultaneously and act as mimetic hormone (FGF21) . It is designed for the research of Type 2 diabetes therapy.