The invention relates to a method for an air-conditioner load actively controlling and participating in peak regulation of electric power. The method is based on thermal inertia of a building, and through the control over start-stop of an air-conditioner, active participation in the peak regulation of the electric power is achieved. The method comprises the following steps that an implement idea of the air conditioner load actively controlling and participating in the leak regulation of the electric power based on the thermal inertia of the building is put forward; thermal dynamic characteristics of a refrigerating building and a duty ratio working mode of the air-conditioner are analyzed and modeling on each of the thermal dynamic characteristics and the duty ratio working mode is conducted; and based on a thermal dynamic characteristic model of the air-conditioner refrigerating building, the air-conditioner load is subjected to coordinating control and a specific scheme of the air-conditioner load actively controlling and participating in the peak regulation of the electric power is obtained. According to the method, by reasonably controlling the air-conditioner load and the building load, dispatch of a grid side can be responded quickly, electric power demand in a peak period is reduced, and contradiction of electric power supply and demand is effectively relieved.