For administrative offenders, there is an overlapping of administrative and criminal unlawfulness. The boundary between them is blurred, and, as a result, the cohesive mechanism between administrative law enforcement and criminal justice is malfunctioning. Previous studies were either too abstract and ambiguous or placed too much emphasis on trivial details of the respective elements of each type of offence and therefore failed to truly clarify the boundary between administrative and criminal unlawfulness. Under the premise of legal interest protection theory, the qualitative difference theory and quantitative difference theory are not completely mutually exclusive. The existence of administrative unlawfulness is indeed a prerequisite for committing an administrative offence, yet the differences between administrative law and criminal law in terms of scope and goal of regulation make it clear that the judiciary is required to draw a line between the scope of administrative unlawfulness and criminal unlawfulness by employing qualitative difference theory and quantitative difference theory respectively. When the nature of protected legal interests of administrative and criminal offence are different, or the protected legal rights in the context of administrative unlawfulness are too abstract, the theory of qualitative difference shall be applied to distinguish between criminal and non-criminal violation; while when the nature of protected legal rights appears to be identical in both administrative and criminal unlawfulness, the theory of quantitative difference shall be applied – that is, to what extent the protected legal right has been harmed – to distinguish between criminal and non-criminal violation and move from one to another, in light of the dependent nature of criminal law.