Abstract: Guided by the theory of Marxist party authority, from the perspective of historical politics, and based on a large number of original historical materials, it is an important field of study on the history of the Communist Party of China to systematically investigate the deep causes, mechanism and historical mirror of the formation of the leadership core of the Communist Party of China during the democratic revolution. During the period of the democratic revolution, the formation of the leadership core of the Communist Party of China is the result of many factors such as social and historical conditions, the characteristics of leaders, and the will of the group, which has historical regularity to follow. The establishment of the first generation leadership core is the key to realize the great mission of national independence and people's liberation, which is mainly reflected in the following aspects: maintaining unification and the unity of the party, effectively strengthening the internal cohesion, centripetal force and external development tension of the party; gathering the great revolutionary forces of the whole Party and the whole nation, striving together to achieve the common revolutionary goal, changing danger into safety and bringing order out of chaos in a time of crisis, destroying the old ruling system in the Liberation War. The useful lessons provided by historical experience are in the following aspects: the core of leadership is very important, which is an important symbol of the maturity of the Communist Party of China; enhance the awareness of core and alignment, consciously maintain the authority of the Party's central committee and centralize the unified leadership; adhere to the unity of "collective leadership" and "leadership core", and implement democratic centralism.