Recombinant Anti-DKK1 x Anti-SOST 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-DKK1 antibody variable domain is fused to the C terminal of an IgG of anti-SOST antibody, or vice versa. The format retains desired characteristics of intact antibodies. This BsAb can bind two factors simultaneously and promote osteoblastogenesis. It is designed for the research of Osteoporosis; Osteogenesis imperfecta (OI); Low bone mineral density; Fracture therapy.