Objective To Summary the clinical characteristics, histological morphology, immunophenotype, diagnostic features, differential diagnosis, treatment and follow-up of SMARCB1 (INI-1)deficient sinonasal carcinoma (SDSC), and deepen the understanding of this disease.Methods The clinicopathologic data of one SDSC patient diagnosed and treated in Shenzhen University General Hospital were retrospectively and literatures were reviewed.Results The patient’s TNM stage was T3N0M0. The computed tomography (CT) and magnetic resonance image (MRI) showed a mass occupying the right nasal cavity and ethmoid sinus with bone destruction. Microscopically, the tumor cells were composed of epithelioid or basal cell-like morphology, most were consistent with mild pleomorphism. The mitotic image was easy to see, no obvious squamous or adenoid differentiation was observed, and a few residual normal mucosal epithelium could be seen around the tumor. Immunohistochemical staining showed that INI-1 nuclear expression of tumor cells was completely absent.Conclusions SDSC is a new subtype of undifferentiated carcinoma of sinuses, which is relatively rare. It is highly invasive with poor prognosis, easy to relapse and early metastasis. INI-1 immunohistochemical detection was performed for the poorly differentiated carcinoma of sinonasal, which was helpful for the accurate diagnosis of this subcategory. Preoperative TPF(Docetaxel+cisplatin+5-fluorouracil) chemotherapy helps to shrink the lesion and facilitate radical surgical excision.