【Abstract】〓Objective〓To investigate the diagnostic value of spiral CT, spectral CT and PETCT scanning in patients with lung cancer.Methods〓Spiral CT, spectral CT, PETCT scanning and serological CEA, CYFRA211 and NSE detection were carried out in 61 patients with suspected lung cancer. The diagnostic value of tumor markers and different scanning methods were compared.Results〓Of the 61 patients, 43 cases (7049%) diagnosed with PETCT, 40 cases（5902%）diagnosed with spectral CT CT and 35 cases（5902%) diagnosed with spectral CT. There were differences of diagnosis rate among the three methods. Of 16 patients with lung adenocarcinoma, 14 patients were found with spectral CT. 13 and 12 patients were found with PET CT and spiral CT. The sensitivity of PETCT and spectral CT scan (9348% and 8696%) were higher than that of spiral CT (7609%, P < 005). The accuracy of PETCT (9180%) and spectral CT (8197%) were much higher than that of spiral CT(6885%, P <005). PETCT and spectral CT for mediastinum metastatic lymph node detection rate (8889% and 7778%) were significantly higher than that of spiral CT (6111%, P < 005). The specificity of PETCT and spectral CT combined tumor markers (8667% and 7857%) were higher than that of spiral CT combined tumor markers (6667%, P < 005). The accuracy of PETCT and spectral CT combined tumor markers (9344% and 8852%) were higher than that of spiral CT combined tumor markers (7869%, P < 005). The sensitivity of spectral CT and PET CT combined tumor markers (9149, 9348) and accuracy (8852, 9180) had no obvious difference (P < 005). Conclusion〓Spectral CT and PET CT in the diagnosis of lung cancer have high sensitivity and accuracy. Spectral CT and PET CT in diagnosis of mediastinal metastatic lymph nodes also have obvious effect. spectral CT combined tumor markers and PETCT combined tumor markers in the diagnosis of lung cancer have similar clinical effects.