A micro-channel heat exchanger comprises: a first manifold and a second manifold; a plurality of micro-channel flat tubes, sequentially connected from top to bottom between the first manifold and the second manifold; and a plurality of heat exchange fins, spaced at a predetermined distance from each other and formed with tube holes for the plurality of micro-channel flat tubes to pass through. The plurality of heat exchange fins have heat dissipation structures. The heat dissipation structures are located above the micro-channel flat tube, and a drainage groove is arranged vertically at the same side of the plurality of heat exchange fins. A portion of at least one heat exchange fin of the plurality of heat exchange fins below the bottommost micro-channel flat tube has a guiding structure for guiding water droplets condensed on the surface of the heat exchange fin to the drainage groove.