Abstract: The effects of the scroll compressor and the variable displacement swash plate compressor on the average temperature in the electric vehicle cabin and the performance of the heat pump air conditioning system were studied under different environment temperature. The experiments were carried out on an experiment platform designed for the heat pump air conditioning system of electric vehicle. The research results show that the average temperature in the cabin increases with time along the rightwards parabolic curve when the heat pump air conditioning system makes use of the variable displacement swash plate compressor, and the temperature increases with time along the upwards parabolic curve when the heat pump air conditioning system makes use of the scroll compressor. At the constant ambient temperature, the cabin comfortable temperature achieves in less time with the increasing of the compressor rotation speed.