The invention discloses a control method and system for dissolved oxygen concentration. The method comprises the following steps: acquiring current aeration control quantity and current dissolved oxygen concentration of an aerobic tank in real time; updating relevant parameter values in a preset prediction model according to the current aeration control quantity, and calculating a dissolved oxygen concentration prediction value of the prediction model; calculating a prediction deviation based on the current dissolved oxygen concentration and the dissolved oxygen concentration prediction value, and correcting the dissolved oxygen concentration prediction value according to the prediction deviation to obtain a dissolved oxygen concentration corrected value; performing rolling optimization based on a preset optimization function and the dissolved oxygen concentration corrected value to calculate an aeration control increment; summating the current aeration control quantity and the aeration control increment, and outputting an aeration quantity control value to an aeration execution module. By adjusting the aeration quantity control value in real time, the purpose of adaptively adjusting tracking is fulfilled to improve the control precision of the dissolved oxygen concentration.