蒙元皇位繼承的紛爭不休，可說是其衰亡的重要因素，因而成為後世學者關注的重點，研究成果豐碩。元成宗(r. 1294-1307)是忽必烈(r. 1260-1294)更改國號後的首位繼立新帝，也是真金(1243-1286)後人掌控皇帝寶座的濫觴，重要性不言可喻。本文探究成宗繼位問題，重新審視與辨析他在繼位前若干具有指標性的政治事件，包括：真金接班的風波、真金子嗣入承大位的確立、成宗即位優勢的形成及其登基的經過，等等。本文指出在這些事件所見世祖朝各方政治力量的升降與重組，特別重視真金遺孀闊闊真(?-1300)扮演的政治角色及其作用，並據以回應或補充前人重要成說。

The disputes over imperial succession in the Yuan dynasty were an important factor in its decline and fall. Among these disputes, the succession of Yuan Chengzong 元成宗 (r. 1294-1307) deserves special attention. Chengzong was the first emperor to succeed after Shizu 世祖 (r. 1260-1294) declared the dynastic name Da Yuan 大元 (Great Yuan), and he was also the first descendant of J̌ingim 真金 to take control of the throne. This paper re-examines several indicative political events before the succession of Chengzong, including the political storm caused by the death of J̌ingim, the tendency of J̌ingim’s sons to become designated as heirs, the formation of Chengzong’s ascendancy and the process of his accession to the throne. It also discusses the rise, fall and reorganization of political forces during Shizu’s reign as seen in the above events, especially the political role played by J̌ingim’s widow, Kökejin 闊闊真.