Objective To establish an animal model of lung adenoma in BALB/c mice based on dynamic characterization by micro-computed tomography (CT). Methods Eighty female SPF-grade BALB/c mice were divided randomly into four groups: model low-dose group (1 mg/g urethane, intraperitoneal [ip], once), model medium-dose group (1 mg/g urethane, ip, once a week, followed by 2 weeks), model high-dose group (1 mg/g urethane, ip, once a week, followed by 4 weeks), and blank group (equal volume of saline). Growth of lung nodules in the mice was monitored regularly using micro-CT. Three-dimensional images of the lungs were drawn using the Analyze 12.0 system, and lung tissues were taken for histopathological examination (hematoxylin and eosin). Results Lung nodules with round high-density shadows were observed at week 11 in all model groups compared with the findings in the blank group. The rate of nodule formation increased with increasing modeling weeks, with rates of nodule formation in the model high-, medium-, and low-dose groups of 93.8%, 93.8%, and 87.5%, respectively, at week 21. Most mice had two to four, followed by one, and one to two nodules, respectively. The average maximum diameter of the lung nodules in the low-dose group was significantly higher than the diameters in the medium- and high-dose groups (P < 0.05), but there was no significant difference in lung nodule volume among the three groups. Regarding pathological type, hematoxylin and eosin staining revealed that the tumors in all the model groups were lung adenomas. Conclusions Lung adenomas were successfully induced in all urethane-dose groups of mice and growth of the lung nodules could be characterized by micro-CT. The rate of nodule formation was highest in the medium-dose group, which developed a moderate number of lung adenomas and provided a stable model, and was thus considered the most suitable model for the study of lung adenomas in mice.