Located in the middle segment of the Three River region, the Yunlong metallogenic belt is considered to be connected with the Southeast Asian giant tin belt. The authors performed LA-ICP-MS zircon U-Pb analysis of two-mica granite closely related to tin mineralization, and got a Late Cretaceous emplacement age of (72.2±0.8) Ma (MSWD=1.9). The genesis of tin deposits in the Yunlong tin metallogenic belt can hardly be explained by one single model(granite-related magmatic-hydrothermal or magmatite-hydrothermal model).Granitic magmatism and tectonic-related magmatism had both contributed to the formation of tin deposits, but they played different roles in different metallogenic periods.