Environmental education is essential for humans to pursue sustainable development. In Taiwan, environmental education is taught to students until they graduate from junior high schools. This study was conducted to establish an assessment system for junior high schools to select appropriate environmental education facilities and sites. A mix of quantitative and qualitative methods, involving literature review and expert in-depth interviews, was employed to establish assessment hierarchy and indicators. Next, the fuzzy hierarchy process was adopted to formulate various assessment criteria and indicator weights, which were then verified. The results of this study can serve as a reference for junior high schools in selecting environmental education facilities and sites, thus achieving the expected outcomes of environmental education.