The Communist Party of China (CPC) has combined Marxist theory with China's specific reality and has formed the theoretical achievements of Marxism to solve the problems in China. The Sinicization of Marxism runs through the different periods of the Chinese revolution and construction led by the CPC. Looking at the course of the sinicization of Marxism, every theoretical achievement in the process of it originates from the CPC's accurate grasp of the transformation of the principal contradictions of Chinese society in a certain period of time. The theory of socialism with Chinese characteristics in the new era is exactly based on the CPC's accurate grasp of the principal contradictions of the Chinese society in the new era.