Abstract: As the important facilities of the energy efficiency buildings, the heat pump air-conditioning has aroused people's wide concern. The use of simulation technology in the field of heat pump has played a very important role in operating characteristics and product innovation of heat pump air-conditioning system. The building load calculation model and air source heat pump system model were studied and built. The building load calculation model was established by dividing the building into several zones. The air source heat pump system calculation model was established including the air source heat pump units, auxiliary heat source and simple construction computation module. And then on the basis of TRESYS software, the building hourly load simulation system was established. The results show that the established dynamic simulation system of air source heat pump is reliability and accuracy. AND it is conducive to the operation and product innovation of the heat pump.