「罪刑法定原則」公認乃源自啟蒙時代之產物，乃為近代重要之刑法原則，亦是一個憲政層次的憲法原則。而罪刑法定原則的具體內涵，是由禁止類推適用、禁止習慣法、禁止溯及既往以及要求明確性四個派生原則所構築而成。另揆諸中國傳統法制，唐律可謂集大成者，後世乃至於明清，其法律雖有所增修，然整體架構仍大致依照唐律而為發展，故本文探討中國傳統法制主要引唐律為研究對象。而對於中國傳統法制中是否具有罪刑法定原則，本文擬從罪刑法定原則之概念、淵源以及發展，進而將其與唐律之相關規範做比較，探討中國傳統法制與近代罪刑法定原則之相似與差異之處，並試圖探討中國傳統法制為何在封建制度下，會出現有類似於罪刑法定原則之規範及原因。

“The principle of punishment according to law” is derived from the product of the Age of Enlightenment recognized, the im portance of the principles of criminal law is for the modern times, is also a constit utional level of constitutional principles. The content of The princi ple of punishment according to law is applicable by prohibition analogy , prohibiting customary law, prohibiting ex post facto law and Clarity of law. On the other hand, traditional Chinese legal system, can be described as a master of the Tang law, later even the Ming and Qing Dynasties, despite the Upgrading its laws, then the overall structure remains substantially to the development of a quasi-Tang law and therefore in this paper discusses the major traditional Chinese Tang law cited for the study. For the Chinese traditional legal system whet her the principle of punishment according to law, and the concept of the principle of punishment according to law in this paper both concl ude its origin and development. And thus it is with the relevant norms of the Tang law of comparison, explored traditional Chinese legal system and Modern crime and similar legal principles of the difference betwee n and tries to explore why traditional Chinese legal system under the feudal system, there will be legal norms and the principle of punishment according to law have similar reas ons.