As the main participators in demand side response,public buildings are difficult to be properly deployed by power grid companies and electricity retail companies in case of its complicated response mechanism. The energy consumption models of building lighting system and air conditioning system faced to demand response are established. On this basis, the number of contracts signed by public buildings and the overall power of a response are estimated respectively. Finally, an example is given to simulate the response of a group of public buildings. The results show that this method can be used to simulate the characters of public building groups responds to price based demand response projects.