Objective To study the value of multi-slice spiral CT (MSCT) enhanced scan in the diagnosis and differential diagnosis of lung cancer. Methods 100 cases of patients with pulmonary space occupying lesions treated in our hospital from February 2012 to February 2015 were treated as the research objects. MSCT plain scan and enhanced scan were performed in all patients. The CT values of MSCT, enhancement peak value and enhancement appreciation of different pulmonary space occupying lesions were compared and were compared with the pathological results at the same time. The sensitivity, specificity and accuracy of MSCT enhanced scan in the diagnosis of lung cancer were analyzed. Results Compared with pathological results, the sensitivity, specificity and accuracy of MSCT plain scan (69.0%, 66.7% and 68.0%) were significantly lower than those of enhanced scan (91.4%, 88.1%, 90%) (P<0.05). There were statistically significant differences in enhancement peak value and enhancement appreciation of lung cancer, inflammatory pseudotumor and pulmonary tuberculoma of three groups (P < 0.01). The differences in CT net enhancement value between squamous cell carcinoma, adenocarcinoma and small cell carcinoma were significant (P<0.01). Conclusion MSCT enhanced scan has higher accuracy, sensitivity and specificity for diagnosis of lung cancer and through observing the imaging findings of MSCT enhanced scan, it can help to differentiate lung cancer from other space occupying lesions to improve the diagnostic accuracy of lung cancer.