〔Abstract〕 Objective To explore the application of 18F-deoxyglucose (18F-FDG) positron emission computed tomography (PECT) in the diagnosis and staging of lung cancer. Methods 95 patients with suspected lung cancer treated in Nanyang Central Hospital from December 2017 to December 2019 were selected. Pathological diagnosis was used as the "gold standard", the diagnostic efficacy of 18F-FDG PET-CT was calculated, and the application of PET-CT phenomenon of lung cancer staging was judged by referring to pathological TNM staging. Results 91 cases of lung cancer, 3 cases of pulmonary tuberculosis, 1 case of pulmonary fibroma, 31 cases of TNM stage I, 27 cases of TNM stage II, 24 cases of TNM stage III and 9 cases of TNM stage IV were diagnosed according to the gold standard. PET-CT imaging showed 88 cases of lung cancer and 85 cases of lung cancer were diagnosed. The diagnostic accuracy and sensitivity were 90.53% and 93.41% respectively. Compared with pathological stages, the diagnostic accuracy of stage I ~ IV were 90.32%, 55.56%, 54.17% and 88.87% respectively. Conclusion 18F-FDG PET-CT imaging has high accuracy in the diagnosis and stage I differential diagnosis of lung cancer, which can serve as a scientific basis for the early diagnosis of lung cancer.