Different economic conditions, national system, social background, humanities and other factors all influence the formation of law. Today's legal system is mainly divided into civil law system and common law system, civil law system and common law system not only in the legal system, but also the understanding of the field of public law. China's current legal system is more similar to the continental law system, so this article is set in Germany. The historical evolution of Germany in the field of public law largely reflects the legal philosophy and mechanism of the original Roman law system, and the change of its constitution and some legislative considerations reflected in the administrative law are worth further study. Especially on the constitutional interpretation of the law, theoretically China and Germany and other civil law countries are similar. This paper analyzes the formation process, development and basic principles of German constitution and administrative law system from legal and historical perspectives.