Sun Shiyi (simplified Chinese: 孙士毅; traditional Chinese: 孫士毅; pinyin: Sūn Shìyì; Wade–Giles: Sun Shih-i, Vietnamese: Tôn Sĩ Nghị; 1720 – 1796), courtesy name Zhizhi (智冶), pseudonym Bushan (補山), was an official of the Qing dynasty who served as the Viceroy of Liangguang[1] and of Liangjiang during the reign of the Qianlong Emperor.

[2] A native of Renhe (present-day Yuhang District, Zhejiang), as a youth, Sun was devoted to study and was said to have prevented drowsiness by knocking his head against a wall.

Awarded a jinshi degree in the imperial examination in 1761, he was secretary to Fuheng during his Burmese expedition, and in 1770 had risen to be Treasurer of Guangxi, when he was cashiered for want of energy, and orders were given to confiscate his property.

In 1788, as Viceroy of Liangguang, he invaded Annam and reinstalled the emperor Lê Chiêu Thống, who had fled in fear of the rebel Nguyễn Huệ.

He was sent to Sichuan to see the supplies of the army fighting in Tibet, into which country he advanced over terrible mountains as far as Chamdo.