Abstract: Based on the indoor environment,the coupling control system of exterior window and air conditioning is proposed,which adds the function of opening window ventilation on the basis of split air conditioner.By controlling the opening degree of the exterior windows,the fresh air volume entering the room can be estimated in advance,the required fresh air load can be calculated,and then the frequency of the air conditioning system can be adjusted to balance the fresh ness of the indoor air and the air conditioning load.The system effectively realizes intelligent and energy-saving control,in line with the future development trend of smart home and requirements for energy-efficient renovation of existing buildings.