Basic law + separate laws and codification are the two modes countries worldwide adopted for enacting environmental legislation in line with their national circumstances and legal traditions. Following the goal of establishing a modern environmental governance system, the mode moderate codification should be China's choice for compiling an environmental code. Moderate codification is a dynamic and open substantive code-compiling mode. Based on idea changes and method innovations, it builds a basic logic system with the goal value as the core and the tool value as the technical method. An environmental code following the moderate codification mode can use the structure of General—Specifics. The General Part extracts common factors and elaborates the legislative purposes, basic principles, management rules and lead measures that dominate the overall situations and are universally applicable. Then each Specific Part (they form Specifics) compiles and integrates the relevant prevailing laws and regulations, and further regulate environmental factors. Therefore, the cornerstone concept of eco-environment should be defined and the environmental legal relationships should be clarified. Environmental code derives from dual source-of-law and considers sustainable development as its value goal, takes the eco-environment as its cornerstone concept, and regards the legal relationship as its systematic tool for constructing its framework system.