The invention discloses a centralized control system for air conditioners. The centralized control system comprises a module unit, an intelligent building control system and a controller. The module unit comprises multiple main control boards corresponding to the air conditioners one to one correspondingly. The intelligent building control system is used for conducting centralized management and monitoring on the module unit. The controller is connected with the module unit and the intelligent building control system, is used for receiving an instruction signal sent out by the intelligent building control system, and conducts corresponding operation processing on the module unit according to the instruction signal. The intelligent building control system is connected with the controller in a butt joint manner, the controller is made into a slave machine, the intelligent building control system conducts centralized management and monitoring on the module unit through the controller, and the management conducted by the intelligent building control system on the module unit can be easy and convenient. The intelligent building control system is connected with the controller, the control scheme and wiring of the intelligent building control system are both simple, cost is low, the main control boards of the air conditioners do not need to be transformed, and workloads are small.