Abstract: This article intends to predict and assess possible hazards of a central air conditioning system in a large subway complex construction project. Design, technical parameters, and corresponding protective measures were audited and assessed in compliance with relevant hygienic standards. The overall plan and designed parameters on indoor temperature and humidity, fresh air vents, return air inlets, air outlets, duct systems, cooling water facility, condensate system, noise reduction measures, and air-conditioning room of this system fundamentally met the requirements of relevant national standards and guidelines. However, certain probable hygienic hazards still exist, thus fresh air volume, garage ventilation, and protection distance from the cooling tower need to be redesigned.