Air conditioner constant temperature control method and air conditioning unit

The invention discloses an air conditioner constant temperature control method and an air conditioner unit. The air conditioner constant temperature control method comprises the steps that the change range of the outdoor environment temperature is divided into a plurality of different temperature intervals in advance; the actual environment temperature of the outdoor unit is detected, and whether the temperature interval of the actual environment temperature changes or not is judged; if yes, when the fluctuation of the inlet and outlet temperature difference t of the outdoor heat exchanger exceeds a set deviation value, the heat exchange area of the outdoor heat exchanger is adjusted; and if not, the current heat exchange area is kept, and the frequency of a compressor and/or a fan of the outdoor unit is adjusted, so that the inlet and outlet temperature difference t of the outdoor heat exchanger is within the target interval. The heat exchange area of the outdoor heat exchanger is adjusted according to the o