Fin and tube type heat-exchanger

Disclosed is a fin and tube type heat-exchanger, which has a number of heat tubes of 6 mm or smaller to cause a reduction of the pressure loss and to prevent a drop in heat-exchange efficiency. Furthermore, the fin and tube type heat-exchanger can obtain the optimum heat-exchange efficiency, reduce the manufacturing cost and adapt to alternative refrigerants. The fin and tube type heat-exchanger comprises: a plurality of cooling fins arranged at predetermined intervals, each cooling fin having a number of joint holes which are formed on the surfaces thereof and arranged in at least one or more stages and a number of slits disposed at spaces between the joint holes formed on each stage in one surface of the cooling fins, each slit having a projecting segment which has an open portion opened correspondingly to the direction of air flow and a pair of standing segments formed at both sides of the projecting segment for guiding the direction of air flow, the projecting segments of the slits being projected in the same direction from the surface of each cooling fin, the slits being grouped by five rows; and, a plurality of heat tubes passing through the joint holes of each cooling fin and joined with the joint holes respectively, each heat tube having the diameter of 5~6 mm or smaller and allowing refrigerant to move therein.