This study developed the Environmental Management System (EMS) for a green casino hotel in Macau. The environmental practices of casino hotels are different from general hotels due to the distinctive patterns. Thus, the application of general EMS in casino hotels is not suitable. The casino hotel EMS indicator was initially selected from ISO 14000 and nine representative green hotel evaluation systems. The Delphi method and systems approach worked with government officials, academics, and hotel managers to modify the questionnaire with 38 experts to determine the preliminary EMS evaluation framework. The results reveal indicators suitable for use, and indicators should be implemented in Macau’s casino hotel industry first. The EMS of this study provides management enlightenment for the government, hoteliers, and consumers to improve environmental management in the systems theory perspective from social, economy, and the natural environment. Keywords: Environmental management system (EMS), green casino hotel, systems theory, Delphi, Macau