The present invention provides a polypeptide able to specifically bind to rare-earth nanoparticles and the use thereof. The polypeptide comprises an amino acid sequence shown by SEQ ID NO: 1 or analogs thereof. The present invention further provides a method for screening a polypeptide having the capacity of specifically binding to rare-earth nanoparticles. The present invention further provides a method for regulating and controlling the in vivo and in vitro autophagy and toxicity of the rare-earth upconversionnanophosphor material, comprising mixing and incubating the polypeptide specifically binding to rare-earth nanoparticles with rare-earth upconversion nanophosphor material, such that the polypeptide specifically binds to the nanophosphor material, wherein the rare-earth upconversion nanophosphor material comprises the rare earth, and the polypeptide specifically binding to rare-earth nanoparticles comprises the amino acid sequence shown by CTARSPWIC (RE-0, SEQ ID NO: 1) or analogs thereof.