The invention discloses a novel tumor marker GSTA1 for lung cancer as well as a screening method and application thereof, belonging to the field of molecular biology and medical science. The marker is characterized in that on the basis of the novel lung cancer specific binding polypeptide acquired by utilizing a bacteriophage random peptide library screening technology at the earlier stage, the polypeptide is used as a probe to select lung cancer associated antigen GSTA1 from a lung cancer cDNA library. The occurrence and development of the lung cancer have a complicated mechanism, the lung cancer involves to the alteration of a lot of lung cancer associated genes and expressions thereof in the primary stage, a plurality of adhesion molecules as well as receptors or ligands can be expressed in a patient body under the effect of a carcinogenic factor, the content of the marker released by the tumor at different development stages is also different, the variation of the specific molecular marker of the tumor cancer is detected from peripheral blood and sputum, advantages of simplicity, rapidness, little pain and easiness in reviewing can be achieved, the novel tumor marker GSTA1 is easy to receive by the patient, and an important significance on the clinical diagnosis for the lung cancer can be achieved. The molecular marker can be provided for the diagnosis and targeted therapy of the lung cancer, a candidate antigen can be provided for the research of the lung cancer tumor vaccine, and the application prospect is wide.