Recombinant Anti-CD20 x Anti-CD22 Bispecific Antibody (Diabody-CH3) is a fusion protein of two diabodies connected together by a CH3 region. In a diabody, the two scFvs with short linkers are from anti-CD20 and anti-CD22 antibodies. The VH and VL domains form an inter-chain pairing. The diabody with different specificities is fused to each of the CH3 chains, which results in 2+2 antigen-binding valency and extends the half-life of this BsAb. This BsAb is designed for the research of Lymphoma; Leukemia; Antoimmune disease; Immune dysfunction disease therapy.