ObjectiveTo explore the key points and difficulties of intraoperative frozen section diagnosis of pulmonary diseases. MethodsThe intraoperative frozen section and postoperative paraffin section results of pulmonary nodule patients in Beijing Chaoyang Hospital, Capital Medical University from January 2021 to January 2022 were collected. The main causes of misdiagnosis in frozen section diagnosis were analyzed, and the main points of diagnosis and differential diagnosis were summarized. ResultsAccording to the inclusion criteria, a total of 1 263 frozen section diagnosis results of 1 178 patients were included in the study, including 475 males and 703 females, with an average age of 58.7 (23-86) years. In 1 263 frozen section diagnosis results, the correct diagnosis rate was 95.65%, and the misdiagnosis rate was 4.35%. There were 55 misdiagnoses, including 18 (3.44%) invasive adenocarcinoma, 17 (5.82%) adenocarcinoma in situ, 7 (35.00%) mucinous adenocarcinoma, 4 (2.09%) minimally invasive adenocarcinoma, 3 (100.00%) IgG4 related diseases, 2 (66.67%) mucinous adenocarcinoma in situ, 1 (16.67%) atypical adenomatous hyperplasia, 1 (14.29%) sclerosing pulmonary cell tumor, 1 (33.33%) bronchiolar adenoma, and 1 (100.00%) papillary adenoma. ConclusionIntraoperative frozen section diagnosis still has its limitations. Clinicians need to make a comprehensive judgment based on imaging examination and clinical experience.