The invention provides a method for controlling the adaptability of the sulfur dioxide discharge amount of a desulfurization system in a power plant, and belongs to the technical field of power generation. In order to solve the problem that in an existing desulfurization device, the pH of slurry is not matched with the SO2 removal rate, the method for controlling the adaptability of the sulfur dioxide discharge amount of the desulfurization system in the power plant comprises the steps that the discharging amount of sulfur dioxide at an outlet of an absorption tower of the desulfurization system is monitored in real time; according to the sulfur dioxide monitored value which is monitored in real time, a pH set value is adjusted; according to the pH set value, the pH control value is adjusted in real time, the pH control value is output to a pH controller of the absorption tower, and control over the adaptability of the sulfur dioxide discharge amount is achieved according to the pH setvalue. The method is used for controlling the sulfur dioxide discharge amount of the desulfurization system.