The present disclosure provides an accumulating/receiving device for a heat pump system. The accumulating/receiving device includes a body, an inlet, a first outlet, and a second outlet. The body defines therein a space. The body is disposed downstream of an outside heat exchanger. The inlet is connected to the outside heat exchanger through a first conduit. The first outlet is connected to an inside heat exchanger through a second conduit. The second outlet is connected, through a bypass conduit, to a third conduit. A liquid of the refrigerant flows out of the body through the first outlet in a cooling mode. A vapor of the refrigerant flows out of the body through the second outlet in a heating mode.