Sandu Shui Autonomous County (Chinese: 三都水族自治县; pinyin: Sāndū Shuǐzú Zìzhìxiàn; Bouyei: Sanyduy Suijzuf Ziqziqxianq) is an autonomous county in the southeast of Guizhou province, China.

[7][8] Sandu administers the following 2 subdistricts and 6 towns:[9] Sandu County's urban center is located 68 kilometres (42 mi) from Duyun, the administrative center of the Qiannan Buyei and Miao Autonomous Prefecture, and 177 kilometres (110 mi) from the provincial capital of Guiyang.

The county is rather mountainous with Karst landscape resulting in large locale temperature and climate differences.

[1] As of 2021, Sandu Shui Autonomous County has a registered hukou population of 380,871, of which, 96,869 belong to urban areas, and the remaining 284,002 belong to rural areas, giving the autonomous county an urbanization rate of 25.43%.

[5] The average annual disposable income for urban residents as of 2021 totaled 35,874 renminbi (RMB), a 9% increase from the previous year, and the second highest among county-level divisions in the Qiannan Buyei and Miao Autonomous Prefecture.