The invention discloses a control method for an air conditioning system, a controller and the air conditioning system, and relates to the field of air conditioners. The method comprises the steps of acquiring detection parameters of all functional zones of an area to be adjusted; comparing the detection parameters of all the functional zones with a parameter threshold value of the corresponding functional zones; and the opening degree of adjusting valves of the corresponding function zones is adjusted according to the parameter comparison result so as to adjust the air supply amount of all the functional zones. According to the control method for the air conditioning system, the controller and the air conditioning system, the power consumption of the air conditioning system of the area to be adjusted can be reduced through zone control.