Objective To analyze the screening results of low-dose CT scan in patients with suspected lung cancer at different ages and explore the clinical application value of lowdose CT scan. Methods 154 cases of patients with suspected lung cancer admitted between January 2016 and January 2017 were retrospectively analyzed performed. According to the patient's age, they were divided into three groups, including below 30 years old (45 cases), 30-55 years old (52 cases), and above 55 years old (57 cases) respectively. And they were given low-dose CT scan and pathological examination. The pathological test results were used as the gold standard to observe the sensitivity, specificity, accuracy and Kappa value of low-dose CT in the diagnosis of lung cancer. The detection of lung nodules by lowdose CT were observed among patients with different age groups. And the tumor growth sites and pathological types were compared among patients with lung cancer at different age groups. Results The sensitivity, specificity, accuracy and Kappa value of low-dose CT in the diagnosis of lung cancer were 0.893, 0.900, 0.896 and 0.791. Solid nodules, partial solid nodules and non-parenchymal nodules were detected in all age groups, and there was a difference in the detection rate of solid nodules (P<0.05), and there was no difference in the detection rates of partial solid nodules and non-parenchymal nodules (P>0.05). The tumors of patients with low-age lung cancer were mostly peripheral type, and the tumors of patients with high-age lung cancer were mostly central type, and there was a difference in growth sites (P<0.05). The patients with low-age lung cancer were mostly adenocarcinoma, and the patients with high-age lung cancer were mostly squamous cell carcinoma, and there was a difference in cancer types (P<0.05). Conclusion Low-dose CT has high accuracy in the diagnosis of lung cancer. It can make an accurate diagnosis of lung nodules types, tumor growth sites and types of lung cancer patients with different age groups.