The Tnh Túc W-Sn ore deposit in Cao Bng, Northeast Vietnam, is located in the Ngn Sn-Tnh Túc metallogenic belt, which is a part of the Northeast Vietnam-Southwest China granite-related W-Sn metallognic belt. SIMS U-Pb dating results of zircons from the granite samples show that the granite was empaced at (93.9±3.0) Ma. Geochemical analysis indicates that the granite is S-type granite, charactered by high SiO2(73.5%~74.6%), peraluminous (Al2O3:14.21%~14.88%), alkali(Na2O+K2O:6.64%~8.47%). The rocks are rich in potassium, but poor in sodium (K2O/Na2O>1). They also have relatively high Rb, Th, U, Zr, Hf, and low Ba, Nb, Sr, Ti, Eu. After comparison with the granites in the Tengchong-Moulmein granite belt and applying the geochemical discrimination of tectonic settings, we conclude that the Gejiu-Dachang granite belt are related to both Pacific tectonic domain and Tethyan tectonic domain; The latter is predominant relative to the former. namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />