Abstract: OBJECTIVE To analyze the effect of chest X-ray combined with CT scan in early screening of pulmonary infection, so as to provide reference for early diagnosis of pulmonary infection. METHODS In our hospital from Jun. 2011 to Jun. 2015, 172 cases of suspected pulmonary infection patients were chosen as objects for the research. They both received chest X-ray and CT examination. Except imaging examination, sputum culture was also done to those patients to make diagnosis. The characteristics of imaging features were observed to figure out the positive rate of pulmonary infection and the accuracy of using combined methods. RESULTS The sputum culture of 92 cases (53.5%) was proved to be positive and the 80 cases (46.5%) were found to be negative. By using chest X-ray combined with CT scan, 45.3% of patients were found to be positive and the accuracy rate was 91.9%, which was significantly higher than single use of chest X-ray (P<0.01). Pulmonary infections in different types had specific CT imaging manifestations. The nonspecific bacterial infection manifested as consolidation opacities, fungal infection showed ground glass opacities, consolidation opacities and nodules, and viral infection showed visible ground glass opacity and line opacity / ground glass, mixed infection manifested as ground glass opacity and consolidation opacity. CONCLUSION Chest CT scan combined with X-ray can further improve the diagnosis of pulmonary infection in early medical screening, so is worthy of wide application. In the future medical screening, patients normal in x-ray examination but are highly suspected as pulmonary infections should receive CT scanning to decrease rate of missed diagnosis.