Southwest Yunnan in China experienced geological evolution similar to the world- famous Southeast Asian tin belt, so the potential of tin mineralization has always been a research hotspot. Based on previous research, this study investigates the temporal and spatial distribution patterns and ore- forming processes of Sn deposits in southwest Yunnan. The tin deposits in southwest Yunnan are mainly distributed in the Tengchong terrane, Baoshan terrane, and Changning- Menglian orogenic belt. Literature geochronological data show that three periods of tin mineralization occurred in the Tengchong terrane, i.e., 125~120 Ma, 75~68 Ma, and 52~47 Ma, respectively. Our recent geochronological data identify two periods of tin mineralization in the Baoshan terrane, including Late Cenozoic (about 32~24 Ma) and Late Cretaceous (~75 Ma), and Triassic (about 235~220 Ma) tin mineralization in the Changning- Menglian orogenic belt. We propose that the Triassic tin mineralization is related to the collision after the closure of the Paleo- Tethys Ocean, the Early Cretaceous tin mineralization is related to the collision after the closure of the Meso- Tethys Ocean, the Late Cretaceous to Paleogene tin mineralization is related to the subduction of the Neo- Tethys Ocean and the subsequent slab rollback, and the Late Cenozoic tin mineralization is related to strike- slip fault activity. Generally, the tin deposits in southwest Yunnan are closely related to the late phase of the composite granite pluton, including fine- grained biotite granite, two- mica granite, or muscovite granite, which are highly differentiated and have low magmatic oxidation states. These characteristics are also shown in the Southeast Asian tin belt. Our research shows that the tin mineralization is significantly later than the emplacement of the ore- bearing Triassic granites in the Baoshan terrane and highlights the need for increased exploration and evaluation of the Late Cretaceous and Cenozoic granites and associated Sn deposits.