Abstract: The history of adapting Marxism to the Chinese context is a history of the Party’s theoretical innovation and creation. A theoretical innovation can be either a gradual theoretical sublimation or a groundbreaking theoretical leap. A theoretical leap is not a theoretical innovation in the general sense, but a qualitative breakthrough based on the quantitative accumulation, and it is a systematic, holistic, and comprehensive theoretical innovation. Xi Jinping Thought on Socialism with Chinese Characteristics for a New Era is the latest development achievement of Marxism in the current stage of the 21st century, and the peak of the development of Marxism in contemporary China, achieving a new leap in adapting Marxism to the Chinese context and the needs of the times. The theoretical leap is not accidental, and its essence and law should be grasped through phenomenon; theory will not leap for no reason, and the reason for its leap can only be found from real life process. The theoretical leap doesn’t happen without any traces, and its traces are always presented through the key theoretical signs. The theoretical leap is about the new change in theoretical coordinates, and it can show the new height reached by a theory in the history of thought. In addition, practice is the fundamental criterion to test a theoretical leap, and the leap in practice lies behind the theoretical leap. To achieve a theoretical leap is the solemn historical responsibility of the whole Party, and Party leaders are the core force to drive a theoretical leap.