Abstract: Sima Yi was one of the four assisting ministers Emperor Wen of the Wei Dynasty had appointed before his death. After Emperor Ming of the Wei Dynasty acceded to the throne, he dispatched Sima Yi to Jingzhou to defend the enemy. Thereafter Sima Yi was appointed the local administrator, thus he was no longer directly engaged in the court’s affairs. Before Cao Zhen’s death, Emperor Ming assigned Sima Yi to the western frontiers to fight against the northern expedition of Zhuge Liang. After Gongsun Yuan rebelled in Liaodong, Emperor Ming dispatched Sima Yi to that prefecture. He demonstrated his trust to Sima Yi’s commanding the army. This emperor did not appoint Sima Yi as one of the assisting ministers before his death, but later let him control the imperial government with Cao Shuang because of the advice of Liu Fang and Sun Zi. During the period of Emperor Ming, Chen Qun and Chen Jiao actually wielded the power and gained the trust of the emperor. However, their attitude towards Sima Yi was somewhat intriguing. Emperor Ming could make use of Sima Yi, but would not go near him. As for Sima Yi’s attitude towards Emperor Ming, he pretended to be loyal to conceal his unfaithfulness, and raised his prestige by contributing in national affairs outside the capital.