There is disclosed a micro-channel heat exchanger, comprising a first header formed with an inlet; a second header spaced apart from the first header, one of the first and second headers being formed with an outlet; flat tubes, two ends of each flat tube being connected with the first and second headers respectively such that a plurality of micro-channels of each flat tube communicate with the first and second headers; fins, each fin being disposed between two adjacent flat tubes; and a return pipe, a first end of which being connected to the outlet formed in one of the first and second headers and a second end thereof being extended towards the other of the first and second headers. The location of the outlet of the micro-channel heat exchanger is easy to change, and the micro-channel heat exchanger is low in cost, compact in structure and easy to install.