The invention discloses a heat exchanger integrally formed by a profiled micro-channel and an external corrugated fin. The heat exchanger comprises a fin group, an upper cover plate, a lower cover plate, a side plate, an air inlet and an air outlet; the fin group is connected in parallel by a plurality of fins; each fin is made of plate material; two sides of the fin is provided with a corrugated fin and the middle part of the fin is provided with a plurality of profiled micro-passage structures; the corrugated fin and the plate material are integrally formed; the upper cover plate and the lower cover plate are respectively provided with a trough which is used for arranging the fin; two adjacent troughs of the upper cover plate and the lower cover plate are communicated with each other intermittently, thus leading the refrigerant to flow through a plurality of fins sequentially; and the profiled micro-passage is a square passage with the side length of 0.8-1mm. The heat exchanger utilizes the micro-pore passage technology, integral external fin technology and no-welding refrigerant high-pressure sealing technology, is applicable to CO2 refrigeration systems, and effectively solves the problem of the high-pressure running of the system. The heat exchanger has compact structure, high heat-exchanging efficiency, small volume, light weight, is made of full-aluminium composite, and greatly reduces the cost.