It is an economic and practical method to provide demand response resources by using the coupled thermal inertia of heating, ventilation and air conditioning systems（HVAC）and buildings. Buildings with active energy storage systems have greater potential to reduce electrical load during demand response. A simulation platform is built and its accuracy is verified, the research is carried out from two aspects：passive energy storage of buildings and air-conditioning and active energy storage of heat storage tank. The flexible combination of three strategies of precooling, temperature reset and shutdown of refrigeration unit is adopted to analyze the demand response potential of buildings, air- conditioning and heat storage tank. The results show that this strategy can meet both short-term（0.5 h）and long-term（2.5 h）demand response. For short-term demand response plans, the thermal inertia of building and air-conditioning system can be used. For long-term demand response plan, active energy storage technology is needed to meet indoor thermal comfort requirements.