Objective: Nasopharyngeal Carcinoma (NPC) is a malignancy of epithelium of epithelium of the nasopharynx, with the highest incidence of otolaryngeal malignancies. A growing number of studies confirm that Circular RNA (circRNA) plays an important role in tumor development, including Hsa circ 0013561. This study aims to elucidate the process and mechanism of NPC regulation hsa circ 0013561.Methods: In this study, circRNA expression nodes and subcellular localization in NPC tissues were analyzed by fluorescence in situ hybridization. The expression of hsa circ 0013561 in NPC cells was further clarified by RT-qPCR. At the same time, the lentivirus vector interfered by hsa circ 0013561 was constructed and transfected. The cell proliferation was detected by CCK-8 method, EdU assay and plate cloning assay. The cell cycle and apoptosis were detected by flow cytometry, and the cell migration ability was detected by wound healing assay and Tran-swell assay. Western blotting examined the expression of apoptosis, Epithelial-Mesenchymal Transition (EMT)-associated proteins, and Janus Kinase/Signal Transductor and Activator of Transcription (JAK/STAT) signaling pathway-related proteins.Results: The results showed that the expression of hsa circ 0013561 in NPC samples was sig-nificantly upregulated and hsa circ 0013561 localized in the cytoplasm. After down-regulating hsa circ 0013561 expression, it significantly inhibited the proliferation and metastasis ability of NPC, inhibited EMT progression, and promoted apoptosis. Further studies showed that inter-ference hsa circ 0013561 significantly inhibited JAK2/STAT3 signaling pathway activation and induced the expression of apoptosis-related proteins.Conclusion: In summary, we found that hsa circ 0013561 is a pro-tumor circRNA in NPC, which can reduce the activation of JAK2/STAT3 pathway by knocking down hsa circ 0013561, thereby slowing down the malignant progression of NPC. Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence: Level 4.(c) 2023 Associacao Brasileira de Otorrinolaringologia e Cirurgia C ' ervico-Facial. Published by Elsevier Espan similar to a, S.L.U.This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).