Structure of heat exchanger

A heat exchanger structure is disclosed including: a plurality of heat exchange fins stacked at predetermined intervals for enhanced thermal conduction; heat transfer tubes perpendicularly penetrating the heat exchange fins so that coolant conveyed there through is heated or cooled; an intake side in which a plurality of slits are cut and raised from a reference surface of the fin in a central portion between the heat transfer tubes with angled edges so that air is directed to the heat transfer tube; and an outlet side having raised slits whose edges are disposed at a larger angle than the intake side, increasing the velocity of air flow passing through the periphery of the heat transfer tube to enhance heat exchange and thereby prevent the flow from being stagnated at the rear of the heat transfer tube.