Objective To investigate the value of non-invasive comprehensive method in diagnosis of primary lung cancer. Methods Medical data of 120 out-patients suspicious for primary lung cancer were analyzed retrospectively. The sensitivity and specificity of non-invasive comprehensive examination method (including chest X-ray, CT, tumor markers, cytology of sputum) for diagnosis of lung cancer were analyzed. Results The sensitivity and specificity only based on clinical symptoms for diagnosis of lung cancer were 11.8% and 25.9% respectively, accuracy 15.0%, false positivity rate 74.1%, and false negativity rate 88.2%. The sensitivity and specificity based on clinical manifestations plus imaging data were 46.2% and 40.7% respectively, accuracy 45.0%, false positivity rate 59.3%, and false negativity rate 53.8%. The sensitivity, specificity and accuracy based on clinical manifestations plus imaging data plus tumor markers plus cytology of sputum reached up to 80.7%, 77.8%, and 80.0% respectively, and the false positivity rate and false negativity rate decreased to 22.2% and 19.3% respectively. Conclusions The non-invasive comprehensive method including clinical symptoms, radiological examinations, tumor markers and sputum cytology has a high sensitivity and specificity for diagnosis of primary lung cancer. The clinicians should give emphasis to the screening of lung cancer to increase its detection rate.