Why cannot the hegemon change the rules of the international order to prevent the growth of the hegemonic rival? Existing theories offer country-level explanations such as economic decline and delusional foreign policy. This paper proposes the rational structural explanation. The logic goes as following: (1) the hegemon can create the rules only when it has an extreme power advantage and other states cannot balance; (2) extreme advantage disappears shortly after war due to recovery (3) some rules backfire; (4) the rational hegemon wants to change “bad rules”; (5) without extreme power advantage, unilateral change of rules provokes balancing; (6) due to high costs of changing the rules, the hegemon declines in the old rules. The argument is tested on the decline of the British hegemony and the rise of the US. It is then applied to the US hegemony and the US support of China’s growth.