Witnessing the crises at the end of the Roman Republic， Cicero not only practically lobbied and mediated between the political forces， but also wrote political philosophies in the hope of theoretically designing a set of programs to maintain the Republic， and his idea of integral law was one of them. Integral law consists of three parts： the civil law， the law of the wise， and the natural law， in which the natural law guides the law of the wise， and the law of the wise guides the civil law，forming a dynamic process of ascent. The civil law of any country or nation has the potential to approach the natural justice in this dynamic process， which can help save the legal degradation caused by political crises， rescuing the law from the toolbox of politicians and making it a powerful weapon to restrain the officials. Moreover， the wide variety of laws existing within the territory of the republic are unified under the supreme leadership of the natural law， which greatly dissolves the division caused by legal differences among ethnic groups or regions. In short， Cicero’s integral law played a role in maintaining the Roman Republic.