Proportion of crime and punishment is one of the fundamental principles of international criminal law that emphasizes the implementation of justice and prevention of injustice in punishment. This principle states that the severity and type of punishment should match the nature and severity of the crime. In international criminal law, courts and international judicial bodies are required to make decisions according to various factors, including the severity of the crime, the role and participation of the accused, the effects of the crime on society and victims, and the specific circumstances of the case. Compliance with this principle not only helps to protect human rights, but also increases the credibility and legitimacy of international judicial systems. At the same time, operational and conceptual challenges such as the precise definition of international crimes and the determination of appropriate criteria for punishments still exist. This article examines the principles and challenges in the proportionality of crime and punishment in international criminal law and analyzes its role in strengthening the international justice system.