The invention belongs to the field of electric power control and particularly relates to a probability model establishing and value solving method of a dispersed modulation strategy of an air conditioner load group. When power vacancy occurs in an electric power system, and the frequency is continuously decreased, a load dispersed control strategy for linearly changing the set temperature of the air conditioners is applied to the air conditioners according to the size of frequency deviation. When the frequency is decreased to the lowest value, the set temperature of the air conditioner will not return back along with the reducing of the frequency deviation, and is kept unchanged at the delta T. When the control time reaches delta tc, the control is finished, and each air conditioner adjust own operation states according to a self-discipline controlled basic mechanism. According to the invention, the dispersed self-discipline control of the air conditioner load cluster response frequency is controlled in a control initial stage; power requirements on the air conditioner cluster response frequency are reduced, power vacancy of the system is filled and amplitude of the frequency reduction is reduced; through the self-discipline control after the control is finished and the air conditioner power returning based on period dividing method, power oscillation and secondary impact can be eliminated, so additional damage to operation of the system can be avoided.