The invention discloses a control method of theair volume and an air conditioning system. The air conditioning system involves an outdoor unit and an air volume adjusting device arranged at the outdoor unit, wherein the outdoor unit comprises a fan; the control method comprises the following steps of collecting the current outdoor temperature and/or the current system energy requirements of the air conditioning system; according to the current outdoor temperature and/or the current system energy requirements, determining the adjusting air volume of the air volume adjusting device; and according to the adjusting air volume, controlling the air volume adjusting device to adjust the air volume of the fan. According to the control method of the air volume and the air conditioning system in theembodiment manner, the adjusting air volume of the air volume adjusting device is determined according to the current outdoor temperature and/or the current system energy requirements of the air conditioning system, and the air volume of the fan is adjusted according to the adjusting air volume, so that the heat exchange amount between a refrigerant and outdoor air is suitable, and the air conditioning system can be ensured to operate in a proper state.