Abstract: Objective: To explore the value of multi-slice spiral CT on differential diagnosis of peripheral lung cancer and focal machine pneumonia. Methods: A total of 50 patients with pathologically confirmed focal pneumonia were selected from January 2014 to January 2018 in our hospital. They were selected as the control group, and the other 60 patients with peripheral lung cancer were selected as the observation group. Multislice spiral CT was used to make a diagnosis. The clinical features, CT signs and CT enhancement characteristics of the two groups were compared. Results: The two groups of sex ratio, basic disease distribution, the difference between the clinical symptoms and laboratory indicators of the proportion of no statistical significance (P>0.05); the observation group of small lesions in the age of the patients was significantly higher than that of control group patients, the difference was statistically significant (P<0.05). There was a statistically significant difference between the control group and the observation group of the patients with large lesions in the cavity and the pleura imaging findings (P<0.05). The CT imaging characteristics of the lesions in the control group and the observation group were statistically significant in the lesion distribution, burr, vascular bundle sign, bronchovascular inflation sign, pleural depressions and structural loosening (P<0.05). The net increment of CT and total CT in the observation group were significantly lower than those in the control group, and the difference was statistically significant (P<0.05). Conclusion: Multi-slice spiral CT scan can show the difference and characteristics of CT imaging signs between focal organizing pneumonia and peripheral lung cancer. Follow-up is necessary for those who cannot be diagnosed, so as to further improve the accuracy of diagnosis.