The increasing cooling load of air conditioning has become the main factor for the increasing peak load of power grid in summer. In order to guide the air conditioning load with huge resources and flexible regulation to participate in the demand response, realize“source load interaction”and ensure the safe and economic operation of power grid, the simulation and practical research on demand response realtime control of building air conditioning is carried out. By establishing the equivalent thermal parameter model of air conditioned room, analyzing the steadystate and dynamic process of air conditioning regulation, considering the indoor and outdoor temperature information and load reduction requirements, the realtime temperature direct control and gradient control simulation of single air conditioning and collective air conditioning are carried out, and the temperature direct control practice is carried out in an office building in Wuhan. The results show that the indoor temperature rises only 1.2 ℃, and the demand response control of air conditioning effectively reduces the load in peak period, which has high regulation value. In addition, the temperature gradient control can achieve a more stable and longterm load cutting effect, inhibit the load rebound phenomenon, and be closer to the requirements of demand response regulation.