The invention provides a sectional type defrosting air conditioner and a sectional type defrosting method. The sectional type defrosting air conditioner comprises an outdoor unit, deicing valves and a compressor, temperature detection equipment is arranged in the outdoor unit, and the top, the middle and the bottom of the outdoor unit communicate with the compressor through the deicing valves correspondingly; and the deicing valves determine whether to be opened or not according to the temperature detected by the temperature detection equipment. The sectional type deicing technology of forward circulation of an air-cooled heat pump is effectively achieved through the sectional type defrosting air conditioner, stable heating is guaranteed, meanwhile, the threshold value is intelligently and automatically adjusted in combination with the air temperature, and accuracy and reliability are achieved; multi-flow-path rapid switching control is carried out, according to different deicing requirements, control output is carried out in a sectional manner, a heat transmission area and an effective heat exchange area are controlled, and accurate forward circulation defrosting and deicing are achieved; efficient intelligent identification and control judgment are achieved, and deicing is fast; and the scheme can be popularized to all use of the machine type.