The utility model relates to a cooling and humidifying device for relieving a heat island caused by waste heat of an air conditioner, which comprises a choke mesh enclosure, a water storage tank, a water mist generating device and a water mist spray head, the choke mesh enclosure is arranged right in front of an air outlet of an air conditioner external unit, and the water storage tank is arrangedbeside the air conditioner external unit and communicated with a condensate water discharge pipe of the air conditioner external unit; the water mist generating device is arranged on the inner side of the air blocking net cover, the water inlet end of the water mist generating device is communicated with the water storage tank through a connecting pipe, the output end of the water mist generatingdevice is communicated with the water mist spray head, the water mist spray head is vertically installed at the bottom of the air blocking cover, and the spraying direction of the water mist spray head is perpendicular to the exhaust direction of an air outlet of the air conditioner outdoor unit. The air conditioner is reasonable in structural design, condensate water generated by operation of the air conditioner is converted into water mist through the water mist generating device, the water mist makes contact with hot air exhausted by the air conditioner outdoor unit, the purposes of increasing air humidity and reducing air temperature are achieved, and the heat island effect problem caused by waste heat of the air conditioner is effectively relieved.