The systems thinking constitutes a pivotal guiding principle for compiling the Ecological and Environmental Code. Drawing insights from this approach, the reconstruction of its “moderate codification” should, under the guidance of “holism” and the “principle of system construction”, clarify the in-depth nature of the Ecological and Environmental Code as a “domain-specific code”. This entails defining it more precisely—beyond its general “domain attribute”—as belonging specifically to the field of “administrative legislation”. Consequently, the “core objective” of codification shall focus on the field of ecological and environmental administration, rather than pursuing a “mixed compilation of multiple legal branches”. In terms of the systematic application of compilation methodologies, the boundaries and extent of “moderation” in “moderate codification” must be clearly delineated to provide actionable guidance for refining the Code’s compilation. Regarding the systematic design of the Code’s structural framework, the scope of its structure and the content to be codified should be defined within the parameters of “moderation”, so as to appropriately enhance the systematic coherence of the Code.