The invention provides a fresh air exchange device, an air-conditioner and an air-conditioner control method. The fresh air exchange device comprises a shell, a fresh air draught fan, a fresh air pipe, an air inlet pipe and an air return pipe, wherein an installing cavity is defined by the shell, the fresh air draught fan is installed in the installing cavity and is provided with an air inlet andan air outlet, the first end of the fresh air pipe communicates with the air inlet, the second end of the fresh air extends to the exterior of the shell, the first end of the air inlet pipe communicates with the air outlet, the second end of the air inlet pipe extends to the exterior of the shell, the air return pipe is installed in the installing cavity, the first end of the air return pipe communicates with the fresh air pipe, the first end of the air outlet pipe is located in the installing cavity, and the second end of the air outlet pipe extends to the exterior of the shell. By means of the fresh air exchange device, the air-conditioner and the air-conditioner control method, power dissipation of the air-conditioner can be reduced while fresh air exchange is carried out, and the influences on the indoor environment temperature are small.