The invention discloses a method for stabilizing a specific surface area of grinding powder, and belongs to the technical field of cement roller press pregrinding. The method comprises the steps as follows: S1, acquiring the specific surface area of the grinding powder and a rotating speed of a powder concentrator, S2, determining pure lag time and inertia process duration from adjustment of the rotating speed of the powder concentrator to variation of the specific surface area of the grinding powder, S3, determining a prediction time domain and a control time domain, S4, establishing an optimization objective function and solving the optimization objective function to obtain optimal variation quantity of the rotating speed of the powder concentrator within the control time domain, S5, calculating a control value of the rotating speed of the powder concentrator in a next step to control operation of the powder concentrator, and S6, substituting a measured value of the rotating speed of the powder concentrator in a next step and a feedback value of the specific surface area of the grinding powder in a next step into the optimization objective function at a next moment and then circularly performing S4-S5. According to the method, the rotating speed of the powder concentrator is adjusted in real time by variation quantity of the specific surface area of the grinding powder and a rotating speed of a circulating fan, so that the specific surface area of the grinding powder is stabilized near a set value; and smooth operation of equipment is facilitated.