The present application provides a heat pump system, comprising a compressor, a first heat exchanger, a second heat exchanger, and a valve device. A first connecting port of the valve device is connected to an exhaust port of the compressor, a second connecting port of the valve device is connected to a first port of the second heat exchanger, a third connecting port of the valve device is connected to an air suction port of the compressor, a fourth connecting port of the valve device is connected to a first port of the first heat exchanger, and a fifth connecting port of the valve device is connected to a fourth port of the first heat exchanger. The valve device is configured to: when the heat pump system is operating in a refrigeration mode, the valve device communicates the third connecting port thereof with the air suction port of the compressor, so that the first heat exchanger acts as a falling film evaporator; and when the heat pump system is operating in a heating mode, the valve device communicates the first connecting port thereof with the exhaust port of the compressor, so that the first heat exchanger acts as a condenser.