Sanjiang Dong Autonomous County (simplified Chinese: 三江侗族自治县; traditional Chinese: 三江侗族自治縣; pinyin: Sānjiāng Dòngzú Zìzhìxiàn; Standard Zhuang: Sanhgyangh Dungcuz Swciyen; Southern Dong: Saml Nyal Dongl Zuc Zil Zil Yenh) is under the administration of Liuzhou, Guangxi Zhuang Autonomous Region, China. It is a region traditionally inhabited by the Dong people, bordering the prefecture-level divisions of Qiandongnan (Guizhou) to the north, Huaihua (Hunan) to the northeast and Guilin to the west.

It has an area of 2,429 square kilometres (938 sq mi) and a population of 297,244.

Sanjiang County is divided into 6 towns, 6 townships and 3 ethnic townships:

20 kilometres (12 mi) north of Sanjiang, toward Hunan province, lies the area of Dong people, Chengyang (程阳), which is a popular destination for backpacker tourism. The area comprises eight traditional Dong minority villages. The houses are all made of wood. Inside the villages you will find traditional drum towers, which were used to announce important things or simply to perform plays to entertain the villagers. Crossing the river is the best preserved Wind and Rain Bridge (程阳风雨桥, chéng yáng fēng yǔ qiáo) which has five parts. The bridge dates to 1912 and is for many people the main reason to visit the village.

North of Chengyang lies the tiny village of Linxia which is interesting because of the local market, but there are no places to stay in Linxia.