Provided is a bispecific recombinant protein, comprising a high affinity tumor-targeting arm and a low affinity fusion protein blocking the interaction of CD47 with SIRPα. The antibody corresponding to the high affinity tumor-targeting arm does not bind to CD47, and its binding affinity to the target antigen on the tumor cell is at least 6 times as great as the binding affinity of monomer fusion protein homodimer corresponding to the low affinity fusion protein blocking the interaction of CD47 with SIRPα, to a CD47 on the tumor cell, wherein the low affinity fusion protein blocking the interaction of CD47 with SIRPα comprises a SIRPα extracellular truncation. Also provided are nucleic acid molecules encoding recombinant proteins and the use of the recombinant proteins and nucleic acid molecules in the manufacture of a medicament for treating tumors.