Xi Rui 郤芮 (d. 636 BCE), courtesy name Zigong 子公, was a nobleman in the state of Jin 晉 during the Spring and Autumn period 春秋 (770-5th cent. BCE), and a member of the house of Xi 郤. Because the name of his fief was Ji 冀 (near modern Jishan 稷山, Shanxi), he is also known as Ji Rui 冀芮. He was a son of Xi Bao 郤豹 and served the dukes Hui 晉惠公 (r. 651-637) and Huai 晉懷公 (r. 637) of Jin as a minister.
In the beginning, he was a supporter of Prince Yiwu 夷吾, who fled during the reign of his father Duke Xian 晉獻公 (r. 678-651), into the land of the Di tribes 狄, yet Xi Rui suggested to him to settle down in the small fief of Liang 梁 (near modern Hancheng 韓城, Shaanxi).
In 651, Duke Xian died, and a succession struggle broke out. Xi Rui, Xi Cheng 郤稱 and Lü Sheng 呂甥 (also written 呂省) suggested to Prince Yiwu to condede the territory of Hexi 河西 to the duke of Qin 秦 in order to find support for his enthronement. The duke of Qin therefore escorted him to the capital of Jin, where he was enthroned as Duke of Jin (i.e. Duke Hui).
As a counsellor to Duke Hui, Xi Rui suggested not to fulfill the promise of ceding territory to Qin. In 650, Duke Hui had Ping Zheng 平鄭 killed, along with Qi Yu 祁舉 and seven other nobles that tried to influence his politics.
Xi Rui and Lü Sheng in turn feared execution when Duke Wen 晉文公 (r. 636-628) mounted the throne in 636 and planned to rebel. Yet the plot was reveiled and he was assassinated by a murderer sent by Duke Mu of Qin 秦穆公 (r. 659-621), who so took a late revenge for Xi Rui's treason.