OBJECTIVE： To observe therapeutic efficacy of diagnostic treatment of molecular targeted drugs for lung cancer. METHODS： 120 cases of suspected lung cancer were selected in our hospital， and were given regular auxiliary examination combined with gefitinib 250 mg，  qd， diagnostic treatment. A treatment course lasted for 4 weeks， and they received 2 courses of treatment. The therapeutic efficacy， symptom improvement， the rate of lung cancer detection， symptom score and quality of life score were observed. RESULTS： The effective rate of all patients was 91.67％， and lung cancer detection rate was 48.33％， two indicators were in high level； after treatment， symptom score of all patients was lower than before， while quality of life score was better than before， with statistical significance  （P＜0.05）. CONCLUSIONS： The diagnostic treatment of molecular targeted drug for lung cancer has a high effective rate and detection rate， and help to improve clinical symptoms and the quality of life.