The invention discloses a comfort control method, a controller and an air-conditioning system. The comfort control method comprises the steps that after the air-conditioning system is started by a user, the current operating mode and operating parameters of the air-conditioning system are obtained, and the current outdoor temperature T4 acquired by an outdoor temperature sensor, the current indoor temperature T1 acquired by an indoor temperature sensor and the current indoor humidity RH acquired by an indoor humidity sensor are obtained; the optimum heat comfort temperature of range [T1, min,T1, max], corresponding to the current operating mode of the air-conditioning system, of the indoor environment is determined according to the human body metabolism rate MR determined in advance, the obtained current operating mode and operating parameters of the air-conditioning system, the current T4, the current T1 and the current RH; and the operating parameters of the air-conditioning system are adjusted till the obtained indoor temperature T1 acquired by the indoor temperature sensor is within the optimum heat comfort temperature range [T1, min,T1, max]. According to the comfort control method, the controller and the air-conditioning system, indoor users can be in the optimum heat comfort state by controlling indoor environment parameters.