Objective To improve the knowledge of pulmonary benign metastasizing leiomyoma.Methods A case of pulmonary benign metastasizing leiomyoma diagnosed in the First Affiliated Hospital of Nanjing Medical University was analyzed.Results A 32-year-old woman suffered from chest stuffiness,heavy pant and weakness after myomectomy in amonth. Chest CT showed miliary shadowwas diffused in both sides of her lungs, but serumtumor marker was normal. When the chest CT result did not change significantly after four-week’s anti-tuberculosis treatment, the patient accepted lung biopsy by thoracoscopic surgery. HE staining showed that the tumor cells had characteristics of smooth muscle cell differentiation.Immunohistochemical staining showed a low proliferation index of tumor cells, which did not indicate theexistence of pulmonary malignant tumor. Smooth muscle actin ( SMA) and desmin as the specific markers of smooth muscle, estrogen receptor ( ER) and progesterone receptor ( PR) were all bly positive, which was the characteristic of pulmonary benign metastasizing leiomyoma. The patient was given the anti-estrogen tamoxifen for 3 months.Without radiological evidence of disease development and further distant metastasis,the patient had been followed up. Conclusions Pulmonary benign metastasizing leiomyoma is a rare disease which can occur in any age group, particularly prevalent among late childbirth women. All patients have uterine leiomyoma history and/ or myomectomy operation, often associated with uterine metastasis, which commonly occurs in lung.