The Third Plenary Session of Eleventh Central Committee of the Communist Party of China (CPC for short) is the greatest turn of far-reaching significance in the history of CPC since the establishment of People’s Republic of China. The session cleared all the undeserved misunderstandings of Mao Zedong Thought and completely rehabilitated it. It is widely accepted that Mao Zedong Thought is the first historic theoretical breakthrough in the sinicization of Marxism while Deng Xiaoping Theory is the second, the jumping-off point of which is this plenary session. The session reestablished the guiding principle of seeking truth from facts, the soul of Mao Zedong Thought. By adhering to the basic principles of Marxism and further sinicizing it according to Chinese realities, the session ushered in a new era of reform and opening movements.