The goal of this study was to establish the evaluation method, which consist of the principle, factor, procedure and checklist, on environmental camp program and then to support staffs of environmental camp for decision-making to improve pre-program and develop new one. The main principles of the evaluation method established in this study were Hierarchical holism and Open inter-communication. First, hierarchical holism focused at the interaction among six factors, which were divided by 3 steps : 1) goal(and objectives) 2) learners and sites 3) activities, staffs and media. Second, open inter-communication could be defined a feedback process among all program participants : manager, staff, teacher, volunteer, learner and so on. The evaluation checklist had been developed of 10 comprehensive items and 30 factor-items at the preliminary step but some items were assessed some complex or duplicate in the result of 3 case studies. The suggested checklist was diminished to 5 comprehensive items and 25 factor-items. Several alternatives, which included specifing learners and objectives, developing site-oriented program and establishing the evaluation sheet were suggested for improving environmental camp program.