The intellectuals with preliminary communist ideology chose Marxism as the way to save the country. They believed that its institutional vision is superior to capitalism, and its plan for transforming the society has realistic feasibility compared with other socialist thoughts. The theory from Russia focused on practical experience. The theory from Japan and Europe focused on scientific principle. The contents they concerned mainly focused on historical materialism, political economy, class struggle, and the conditions for the realization of communism. In addition to Marx and Engels, these intellectuals also read the theoretical works of Lenin, Bukharin, Hajime Kawakami, Kautsky and others. In the process of accepting and using the theory, the demand from the country and the example from the Soviet Union played an important role.