The present invention proposes a micro-channel heat exchanger (100). The micro-channel heat exchanger comprises: a first manifold (110) and a second manifold (120); a plurality of micro-channel flat tubes (130), sequentially connected from top to bottom between the first manifold and the second manifold; and a plurality of heat exchange fins (140), spaced at a predetermined distance from each other and formed with tube holes for the plurality of micro-channel flat tubes to pass through, wherein the plurality of heat exchange fins are provided with heat dissipation structures (150) for increasing the heat exchange area, where the heat dissipation structures are located above the micro-channel flat tube, and a drainage groove (16) is arranged vertically at the same side of the plurality of heat exchange fins, wherein, a portion of at least one heat exchange fin of the plurality of heat exchange fins below the bottommost micro-channel flat tube is provided with a guiding structure (170) for guiding water droplets condensed on the surface of the at least one heat exchange fin to the drainage groove. The present invention also proposes a heat pump system configured with the micro-channel heat exchanger. The micro-channel heat exchanger according to the present invention can effectively prevent accumulation of condensed water at the bottom of the heat exchange fins.