The present invention discloses a heat pump appliance including a refrigerant circuit operable in a plurality of modes to transfer heat between an exterior atmosphere and an interior atmosphere via a refrigerant. The refrigerant circuit includes a compressor for compressing the refrigerant, a first heat exchanger for transferring heat between the refrigerant and the interior atmosphere, a throttling device for lowering the pressure of the refrigerant, and a second heat exchanger for transferring heat between the refrigerant and the exterior atmosphere. Wherein, the first heat exchanger operates as a condenser to cool the refrigerant in a heating mode and operates as an evaporator to vaporize the refrigerant in a cooling mode, the second heat exchanger operates as an evaporator in the heating mode. The appliance further includes a third heat exchanger connected in the refrigerant circuit and positioned near the second heat exchanger. The third heat exchanger is selectively hydraulically communicated with the first heat exchanger for transferring heat released by the refrigerant at the first heat exchanger to the refrigerant at the third heat exchanger in a defrosting mode, thereby pre-heating the refrigerant entering the second heat exchanger. In this way, the heat energy condensed in the first heat exchanger can be partially used to defrost the coil-type second heat exchanger 14, so there is no need to reverse the refrigerant cycle in the defrosting mode.