Abstract: As an application of act-utilitarianism to criminal law theory, view of substantive criminal law faces up to the fact of legislation and justice and can help us understand the purpose of criminal law. It has surpassed deontology which only talks about criminal law abstractly. But it has the following limits. Owing to not distinguish the level of intuitive thinking from the level of critical thinking, it confuses the two roles of legislator and justice; it only pays attention to the flexible application of the rules of criminal law, not to consider the long-term results of abiding by the rules of criminal law, so it violates the principle of a legally prescribed punishment for a specified crime; and it emphasizes results excessively and neglects justice, thus it has the feature of injustice.