The invention relates to a method for preparing activated carbon with a large specific surface area through rapid activation. The activated carbon with a large specific surface area is prepared through rapidly activating high-carbon raw materials, such as anthracite, petroleum coke and the like, by auxiliaries and alkali together. The method comprises the steps of uniformly mixing the high-carbon raw materials, the activating auxiliaries and KOH, so as to obtain an alkali-carbon mixture, and heating the alkali-carbon mixture under the protection of an inert atmosphere, so as to obtain an activation product; quickly cooling the activation product to room temperature under the protection of the inert atmosphere; washing the activation product with water, and drying, thereby preparing the activated carbon with a large specific surface area. According to the method, the activation temperature is low, the activation time is short, a relatively high yield of activated carbon with a large specific surface area is obtained under the condition of a lower alkali/carbon ratio, the utilization ratio of alkali, carbon and energy is increased, the production cost is reduced, and the pollution is reduced.