Yanyuan County, belonging to Liangshan Yi Autonomous Prefecture of Sichuan Province, is located in the west of Liangshan Prefecture, the southeast edge of the Qinghai-Tibet Plateau, and the west bank of the lower reaches of the Yalong River, with longitude of 100 ° 42 ′ - 102 ° 03 ′ E and latitude of 27 ° 06 ′ - 28 ° 16 ′ N. It faces Xichang City, Dechang County and Miyi County across the Yalong River in the east, Yanbian County in the south, Ninglang Yi Autonomous County in Yunnan Province in the west, and Muli Tibetan Autonomous County and Mianning County in the north. It covers an area of 8398.6 square kilometers, including 1049 square kilometers of basin area.

In the sixth year of Yongzheng's reign in the Qing Dynasty (1728), Yanjingwei was changed to Yanyuan County. In the first year of the Republic of China (1912), Yanyuan County was still established and Yanzhong (Youjun Town, Xichang City) was under the jurisdiction of Yanyuan County. In the 28th year of the Republic of China (1937), it was subordinate to the Ningzhi Reclamation Committee. In 1950, Yanyuan was under the jurisdiction of Xichang District. In 1952, Yanyuan County was moved from Weicheng to Yanjing. In 1964, it was changed to Yanyuan Yi Autonomous County. In 1978, Xichang was merged into Liangshan Yi Autonomous Prefecture and renamed Yanyuan County.

The GDP of Yanyuan County increased from 11.034 billion yuan in 2015 to 13.729 billion yuan in 2020. As of June 2021, Yanyuan County has jurisdiction over 23 townships and 1 street (6 townships, 17 towns and 1 street), 145 organic villages, 22 communities and 1280 village (residential) groups, and the county government is located at 56 Government Street. As of January 2022, there are about 390000 people living in Yanyuan County, including 21 ethnic groups, including Han, Yi, Mongolian, Tibetan and Hui.