Objective To investigate the application value of multi-slice spiral CT lowdose scanning in the diagnosis and differential diagnosis of small pulmonary nodules. Methods A total of 120 persons receiving chest CT scan in the hospital from June 2015 to May 2017 were selected as study subjects, and they were divided into the control group and the observation group with 60 cases in each group by the random number table method. The control group was examined by chest multi-slice spiral CTconventionaldose scanning while the observation group was examined by multi-slice spiral CT lowdose scanning. The detection rate of small pulmonary nodules and the detection of benign and malignant small pulmonary nodules in the two groups were observed, and the safety of the two methods was compared. Results There were pulmonary nodules in 50 cases in the control group and the detection rate of small pulmonary noduleswas 84% (42/50). However, there were pulmonary nodules in 48 cases in the observation group and the detection rate of small pulmonary nodules detection rate was 81.25% (39/48)(P>0.05). There was no significant difference in the detection rates of small benignpulmonary nodules, instability and suspected deterioration between the observation group and the control group [9.52% (4/42), 78.57% (33/42), 11.90% (5/42) vs 10.26%(4/39), 76.92% (30/39) and 12.82% (5/39)] (P>0.05). The CTDIw and DLP of chest CT scan in the observation group were significantly smaller than those in the control group(P<0.05). Images of the two groups showed similar clarity of the size, shape and internal structures of small pulmonary nodules. Conclusion Multi-slice spiral CT low-dose scanning is of definite application valuein the diagnosis and differential diagnosis of small pulmonary nodules, with high safety. It is suitable for clinical health examination.