Ogedai was the second Great Khan during the Mongol period. He inherited the unfinished work of Genghis Khan and initiated the establishment of the Great Mongolia. He has an important position as a link between the past and the future. There are currently few research works on this figure and his era in the academic community. This book analyzes Ogodei Khan's way of ruling the Great Mongolia and the changes in the country during this period from the aspects of military arrangements, administrative systems, economic measures and family relationships. Ogedei successfully dealt with the threats posed by the younger son's forces, maintained the solemn power of the Khan and centralized power, built the institutional framework of the Great Mongolia, absorbed a large number of external personnel and systems, and promoted the sustainable development of the Great Mongolia. Ogedei provided the subsequent Mongol Khan with rich experience in handling internal and external affairs.