Abstract: The Communist Party of China (CPC) has always been competent at resolving the basic theoretical problems at different times，thereby driving forward the theoretical innovation of the Party.As a product of the sinicization of Marxism and the Party′s theoretic innovation，Mao Zedong Thoughts used to provide a practical guideline for the new democratic revolution.Now，the theoretical system of socialism with Chinese characteristics，an answer to the construction of socialism and the Party itself，just addresses itself to the very problems of how to build such a socialism at a time when opportunities and challenges exist side by side in this 21st century.Such achievements，with special features of the historical periods that they represent，constitute the powerful engine to propel the construction of the Party.

Key words: theoretical innovation, construction of CPC, engine, Mao Zedong Thoughts, Deng Xiaoping Theory, the Ideology of “Three Represents”, the Scientific Outlook on Development