SMARCA4-deficient thoracic sarcoma?(SMARCA4-DTS) is a rare malignant tumor which is mainly occurred in the chest. It has the characteristics of striated morphology and characteristic immunophenotype and molecular type. In China, there are only 6 literature reports[1，2]. Among the new types of breast tumors in the fifth edition of the World Health Organization (WHO), SMARCA4-DTS occupies one place. The mutation rate of smarca4 gene encoding in NSCLC is about 3-8%, and its homozygous deletion, fusion or truncation mutation is closely related to protein deletion and higher tumor mutation load [3,4]. The comparative analysis and identification of SMARCA4-deficient NSCLC and SMARCA4-DTS are also the hot topics in recent years. The type of tumor is aggressive and prone to distant metastasis. Radical operation is the first choice in the treatment principle, and the combined treatment of postoperative auxiliary radiotherapy and chemotherapy is preferred. A case of left upper lobectomy in our hospital recently was treated. The pathological and immunohistochemical results were in line with the SMARCA4-DTS. This paper reports and reviews the literature.