Recombinant Anti-FGFR1 x Anti-KLB Bispecific Antibody (Tandem Fab) is designed to be expressed as three chains derived from the variable domains of anti-FGFR1 and anti-KLB parental antibodies. It contains a His-tag for affinity purification. And the two Fd regions are connected by a flexible linker. This BsAb can bind two factors simultaneously and act as mimetic hormone (FGF21) . It is designed for the research of Type 2 diabetes therapy.