A control method for an air conditioning system includes: calculating an average heat exchange amount of a coil according to real-time operation information; setting a full-load air volume parameter and a full-load water volume parameter in a heat exchange model according to the real-time operation information and the heat exchange model, and calculating a full-load heat exchange amount; calculating a dynamic margin value based on the average heat exchange amount and the full-load heat exchange amount; determining whether the dynamic margin value is greater than a first preset condition or less than a second preset condition, so that the controller outputs a first control signal or a second control signal respectively to adjust a coil water inlet temperature; and when the dynamic margin value is less than the first preset condition and greater than the second preset condition, maintaining the current setting state.