He served his nephew King Wuling 趙武靈王 (r. 326-299), but was opposed to the military reform of King Wuling during which a unit of mounted archers was created that was modeled after the fighting units of the nomad tribes in the north. Prince Cheng was of the opinion that a deviation from ancient patterns would destroy the loyalty of the troops towards their lord, yet later on the King convinced him that a reform was of great tactical advantage.
King Wuling in 299 retired and gave the throne to his son Prince He 何, who is known as King Huiwen 趙惠文王 (r. 299-266). The former Heir Apparent, Prince Zhang 公子章, thereupon rose in rebellion. Prince Cheng killed the usurper and besieged the mansion of the King Father (King Wuling), where Prince Cheng had originally fled to. Fearing that he would be punished when he lifted the siege, Prince Cheng continued to close in the King Father until he starved to death. In the aftermath he was appointed counsellor-in-chief (xiang 相) of King Huiwen.