Abstract: The article briefly comments on the merits and deficiencies of the theory of the joint crime in mainland China's law system and the various opinions concerning one-sided accomplice in the field of criminal studies. Then the article analy zes the necessity of taking one-sided accomplice as one form of the joint crim e in the current judicial context and the rationale forit based on the consti tutes of crime. Finally the articleelaborates on the different types of one-sid ed accomplice and the corresponding criminal responsibilities.