Cao Xi (died 249) was the second son of Cao Zhen, an officer who served the Kingdom of Wei during the Three Kingdoms era of Ancient China. Cao Xi was also the younger brother of Cao Shuang.
Cao Xi was part of Cao Shuang's clan. Aware of Sima Yi's intentions of usurping power, Cao Xi eliminated the clan to warn his arrogant elder brother to be more alert, but Cao Shuang ignored him. After Sima Yi's successful coup, Cao Xi was executed, along with the rest of Cao Shuang's clan for treason.