An Sishun (安思順) (died April 6, 756[1]) was a general of the Chinese Tang dynasty during the reign of Emperor Xuanzong, probably of Tujue (Göktürk) extraction.
In 751, after Emperor Xuanzong met with and was impressed by the ethnically Goguryeo general Gao Xianzhi, who was then military governor of Anxi Circuit (安西, headquartered in modern Aksu Prefecture, Xinjiang), he issued an order making Gao the military governor at Hexi.
In 752, in the middle of a rebellion by the Tujue chieftain Li Xianzhong (李獻忠), the chancellor Li Linfu, who was then locked in a power struggle with fellow chancellor Chen Xilie and did not want to leave the capital Chang'an to react to the rebellion (as he was also the military governor of Shuofang), resigned his governorship of Shuofang and recommended An to take over for him.
Meanwhile, a rivalry had arisen between An Sishun and his cousin An Lushan, then the military governor of Fanyang Circuit (范陽, headquartered in modern Beijing) and the general Geshu Han, then the military governor of Longyou Circuit (隴右, headquartered in modern Haidong Prefecture, Qinghai).
After An Lushan did rebel early in 755, Emperor Xuanzong did not punish An Sishun, but recalled him to Chang'an to serve as the minister of census (戶部尚書, Hubu Shangshu).