Abstract: The core of Sun Yat-seng' s ideology of the Principle of Democracy is to establish a bourgeois democratic republic to guarantee the people's full enjoyment of freedom and democracy, and to eliminate the pernicious influences of feudal tyranny with an ultimate aim to transfer the state power from the feudal emperor to all the people of China. The realization of the Principle of Democracy is one of Sun Yat-seng's dreams, for which he had struggled all his life. Sun Yat-seng's ideology of the Principle of Democracy is mainly composed of the following: the adocacy of democratic republicanism, the theory of revolutionary courses, the advocacy of equality and freedom, the etsablishment of a political system by the whole people, the distinguishability of state powers from the state functions, the specification of the Five Rights in the constitution, and the local autonomy.