Recombinant Anti-CD89 x Anti-S. pneumoniae Bispecific Antibody (Diabody) is designed to be expressed as two polypeptide chains respectively. The two chains are cross-over pairing to form a dimer. It contains a His-tag for affinity purification. This BsAb can retarget NK cells to genus plasmodium. It is designed for the research of S. pneumoniae infection therapy.