Abstract: The provisions of the basic national policy on environment in the "Constitution of the People's Republic of China", that is, the basic national policy on constitutional environment, carry the feature of objective legal order, and is the highest logical line for the codification and systematization of environmental law. In the era of "ecological civilization", the codification of environmental law is confronted with the dilemmas of categorization, decodification and normativity. The constitutional doctrine of the basic national policycan plays the role of goal guidance, boundary control and content formation of environmental codification. The basic national policy with certain orientation on cons-titutional environment can promote the consistency of the system and value of environmental codes, coordinate their normative binding force and structural openness and dynamically optimize the "appropriate codification" model. On the other hand, the element-based basic national policy on constitutional environment can regulate and guide the ge-neral and specific provisions of the environmental code, which not only imposes "common but differentiated" obligations of environmental protection on the state's public power, but also protects citizens' environmental rights and interests through "reflexive interests". In the long run, it is necessary to strengthen the research transformation of "constitution-oriented environmental law" under the guidance of codification and systematization and properly handle the internal and external structural relationship between the codes of environmental law and other departmental codes such as the basic administrative code.