Sunan Yugur Autonomous County (Chinese: 肃南裕固族自治县) is an autonomous county under the administration of the prefecture-level city of Zhangye, Gansu Province, China, bordering Qinghai province to the south. It is home to the majority of the Yugur ethnic group. The seat of government is in the town of Hongwansi [zh] (红湾寺镇).

The autonomous county spans an area of 20,176.7 square kilometres (7,790.3 mi²), and is home to a total population of 39,283 as of 2021. The autonomous county is ethnically diverse, with large populations of Han Chinese, Yugurs, and Tibetans, with none comprising a majority.

Sunan Yugur Autonomous County consists of three separate areas: Mínghua District, situated in the plains in the northwest, and Huángcheng District, situated in the mountains in the southeast, are separated from the main part of the county.^{[citation needed]}

The autonomous county's name refers to its location to the south (Chinese: 南; pinyin: nán) of Suzhou (Chinese: 肃州; pinyin: Sùzhōu), the former name of Jiuquan.

Sunan Yugur Autonomous County was established in 1954.

Sunan Yugur Autonomous County is located in the middle portion of the Hexi Corridor, along the northern foot of Qilian Mountains. The autonomous county is particularly long and narrow, extending just 120 kilometres (75 mi) to 200 kilometres (120 mi) from north to south, but spans over 650 kilometres (400 mi) from east to west.

The autonomous county is bordered by Bairi Tibetan Autonomous County to the east and Subei Mongol Autonomous County to the west. The autonomous county's northern border is formed by Liangzhou District, Suzhou District, Jiayuguan, and Yumen from east to west. Sunan Yugur Autonomous County is bordered by Menyuan Hui Autonomous County of Qinghai to the south.

The physical geography of the region includes many mountains, canyons, and alluvial plains. The southern portion of the autonomous county is more mountainous, while the northern portion includes more plains. Elevation within Sunan Yugur Autonomous County ranges from 1,327 metres (4,354 ft) to 5,564 metres (18,255 ft) above sea level, with an average elevation of about 3,200 metres (10,500 ft) above sea level. Prominent mountains within the autonomous county include Suzhu Lian (Chinese: 素珠链; pinyin: Sùzhū Liàn) and the July 1 Glacier. Major rivers that flow through Sunan Yugur Autonomous County include the Ruo Shui, the Shiyang River, and the Shule River.