Provided in the present invention is a small molecular peptide capable of binding specifically with lung cancer cells the peptide is a molecule with 8 amino acids containing the structure of XGXG, wherein G is L-glycine and X is one of 20 amino acids. Also provided in the present invention are a small molecular probe obtained by labeling the above-mentioned small molecular peptide with isotope 99mTc, a small molecular radio-therapeutic agent targeting lung cancer obtained after labeling the above-mentioned small molecular peptide with isotope 131I and preparation methods for the above-mentioned probe and therapeutic agent.
