Yunnan is China's most diverse province, biologically as well as culturally. The province contains snow-capped mountains and true tropical environments, thus supporting an unusually full spectrum of species and vegetation types. During summer, the Great Plateau of Tibet acts as a barrier to monsoon winds, trapping moisture in the province. This gives the alpine flora in particular what one source has called a "lushness found nowhere else."

This topographic range combined with a tropical moisture sustains extremely high biodiversity and high degrees of endemism, probably the richest botanically in the world's temperate regions. Perhaps 17,000 species of higher plants, of which an estimated 2,500 are endemic, can be found in the province. The province is said to have "as much flowering plant diversity as the rest of the northern hemisphere put together".

The fauna is nearly as diverse. Yunnan Province has less than 4% of the land of China, yet contains about half of China's birds and mammals.

Ethnic groups are widely distributed in the province. Some twenty-five minorities live in compact communities, each of which has a population of more than five thousand. Ten ethnic minorities living in border areas and river valleys include the Hui, Manchu, Bai, Naxi, Mongolian, Zhuang, Dai, Achang, Buyei and Shui, with a combined population of 4.5 million; those in low mountainous areas are the Hani, Yao, Lahu, Va, Jingpo, Blang and Jino, with a combined population of 5 million; and those in high mountainous areas are Miao, Lisu, Tibetan, Pumi and Drung, with a total population of four million.