In 238, Cao Rui grew ill. He created Consort Guo empress in preparation of allowing her to become empress dowager after his death. He initially wanted to entrust his adopted son, Cao Fang the Prince of Qi, to his uncle Cao Yu, to serve as the lead regent, along with Xiahou Xian (), Cao Shuang, Cao Zhao (), and Qin Lang (). However, his trusted officials Liu Fang () and Sun Zi () were unfriendly with Xiahou and Cao Zhao and were apprehensive about their becoming regents, and managed to persuade him to make Cao Shuang (with whom they were friendly) and Sima Yi regents instead. Cao Yu, Cao Zhao, and Qin were excluded from the regency. In the spring of 239, Cao Rui created the seven-year-old Cao Fang crown prince, and died the same day of that creation. Cao Fang succeeded him as emperor.