Yunnan is the most southwestern province in China, with the Tropic of Cancer running through its southern section. The province has an area of 394,000 square km, 4.1% of the nation's total. The northern part of the province forms part of the Yunnan-Guizhou Plateau.

The province borders Guangxi Zhuang Autonomous Region and Guizhou Province in the east, Sichuan Province in the north, and Tibet Autonomous Region in the northwest. It shares a 4,060 km border with Myanmar in the west, Laos in the south, and Vietnam in the southeast.