A method for controlling a combi-boiler, wherein the combi-boiler comprises a first heat exchanger 1, a flow distributor, a domestic heating branch, a water heating branch and a bathroom pipe, the flow distributor having a water inlet connected to the first heat exchanger, a heating outlet communicated with the domestic heating branch and a heat supply outlet communicated with the water heating branch, and the bathroom pipe exchanging heat with the water heating branch; the method for controlling the combi-boiler comprises: controlling the heating outlet to be closed and the heat supply outlet to be opened in response to receiving a bathroom water demand signal; acquiring a water temperature of a bathroom outlet; acquiring a duration for which the water temperature at the bathroom outlet keeps within a preset water temperature range; controlling an open degree of the heat supply outlet to decrease and an open degree of the heating outlet to increase, in accordance with a determination that the duration is greater than or equal to a first preset duration, and a heat load of the combi-boiler is lower than a rated load; and controlling the heat load of the combi-boiler to increase, and maintaining the water temperature at the bathroom outlet within the preset water temperature range, wherein controlling the opening degree of the heat supply outlet to decrease and the opening degree of the heating outlet to increase, in accordance with a determination that the duration is greater than or equal to the first preset duration, and the heat load of the combi-boiler is lower than the rated load comprises: controlling the flow distributor to be adjusted gradually towards the heating outlet, such that the opening degree of the heat supply outlet decreases gradually and the opening degree of the heating outlet increases gradually, in accordance with a determination that the duration is greater than or equal to the first preset duration, and the heat load of the combi-boiler is lower than the rated load; controlling the heat load of the combi-boiler to increase, and maintaining the water temperature at the bathroom outlet within the preset water temperature range comprises: each time the flow distributor is adjusted towards the heating outlet, controlling the heat load of the combi-boiler to increase, and maintaining the water temperature at the bathroom outlet within the preset water temperature range; and ceasing adjusting the flow distributor when the heat load of the combi-boiler reaches the rated load 2. controlling the heating outlet to be closed and the heat supply outlet to be opened in response to receiving a bathroom water demand signal; acquiring a water temperature of a bathroom outlet; acquiring a duration for which the water temperature at the bathroom outlet keeps within a preset water temperature range; controlling an open degree of the heat supply outlet to decrease and an open degree of the heating outlet to increase, in accordance with a determination that the duration is greater than or equal to a first preset duration, and a heat load of the combi-boiler is lower than a rated load; and controlling the heat load of the combi-boiler to increase, and maintaining the water temperature at the bathroom outlet within the preset water temperature range, wherein controlling the opening degree of the heat supply outlet to decrease and the opening degree of the heating outlet to increase, in accordance with a determination that the duration is greater than or equal to the first preset duration, and the heat load of the combi-boiler is lower than the rated load comprises: controlling the flow distributor to be adjusted gradually towards the heating outlet, such that the opening degree of the heat supply outlet decreases gradually and the opening degree of the heating outlet increases gradually, in accordance with a determination that the duration is greater than or equal to the first preset duration, and the heat load of the combi-boiler is lower than the rated load; controlling the heat load of the combi-boiler to increase, and maintaining the water temperature at the bathroom outlet within the preset water temperature range comprises: each time the flow distributor is adjusted towards the heating outlet, controlling the heat load of the combi-boiler to increase, and maintaining the water temperature at the bathroom outlet within the preset water temperature range; and ceasing adjusting the flow distributor when the heat load of the combi-boiler reaches the rated load 2.