Objective: To study the clinic pathological characteristics, diagnosis and differential diagnosis of bronchiolar adenoma. Methods: Ten cases of bronchiolar adenoma in Lu′an people′s Hospital were collected from January to December 2020, and their clinical data, imaging results, histopathological features and immunohistochemical phenotype were analyzed with literature reviewed. Results: Of the patients, there were 4 males and 6 females, with age ranging from 49 to 79 years old. Most patients had no obvious clinical symptoms, and were found occasional pulmonary nodules by chest CT examination, with ground glass nodules on CT. All of the lesions were located in the periphery of the lung. Grossly, all of the tumors were well circumscribed, solid, and tan to brown on the cut surface. Six cases were the proximal type, and four case was the distal type. Microscopically, the tumor showed glandular, flat and papillary growth pattern, and a large amount of extracellular mucus could be seen. The lining cells of the cavity margin were mucous cells, ciliated cells, non-ciliated cuboidal cells and Clara cells. There was no atypia and mitosis. Continuous basal cell layer could be seen outside the cavity margin, and some tumors could be free of mucous cells and ciliated cells. Immunohistochemical staining of p40, p63 and CK5/6 showed the continuous basal cell layer. Conclusions: Bronchiolar adenoma is a kind of peripheral lung tumor composed of double-layer cells, the diagnosis requires the existence of a complete basal cell layer, and sometimes it is difficult to make a definite diagnosis. The existence of basal cell layer which is identified by immunological histochemistry (p40、p63 and CK5/6) is the key point for distinguish BA from lung adenocarcinoma.