Anti-FN1 x Anti-HSG Bispecific Antibody (IgG-IgG) is designed to be generated by crosslinking two full length IgGs, anti-FN1 and anti-HSG parental antibodies. A stable linkage is formed between the two antibodies. This BsAb can be used in pretargeting system of PET, radioimaging or radiotherapy. It can mediate targeting of radioactivity to tumor cells. It is designed for the research of Solid tumors imaging and therapy.