The present invention discloses a dimeric polypeptide radiopharmaceutical targeting integrin α6 and a preparation method thereof. The radiopharmaceutical comprises a cKiE dimer polypeptide and a radionuclide, wherein the radionuclide is labeled with the cKiE dimer polypeptide through a bifunctional chelating agent; the cKiE dimer polypeptide is dimerized by two cKiE polypeptide monomers connected by a linker; the cKiE polypeptide monomer is a cyclic polypeptide, and the cyclic polypeptide is composed of an amino acid molecular chain with the sequence of Lys-Arg-Trp-Tyr-Asp-Glu-Asn-Ala-Glu connected head to tail; the linker is an amino acid molecular chain in which 3-5 inert amino acid molecules are sequentially connected or a polyethylene glycol with a polymerization degree of 3-12, and the inert amino acid is glycine or serine. The cyclic polypeptide sequence of the radiopharmaceutical of the invention will not be recognized by proteases in vivo, and can effectively improve the in vivo metabolic stability, thereby improving the uptake of tumor tissue.
