Recombinant Anti-CD22 x Anti-saporin Bispecific Antibody (F(ab')2-scFv2) is designed to be expressed as two chains combined via a hinge region. The scFv of the anti-CD22 specificity is fused to the C terminus of the anti-saporin Fab fragment, or vice versa. This format comprises four binding sites (two same scFv regions and two same Fab fragments), two for each antigen. This BsAb can be used in pretargeting system and deliver immunotoxin to tumor cells. It is designed for the research of Lymphoma therapy.