Abstract: A heat-exchanging fin device serves for enhancing heat exchange efficiency. The fin device comprises at least two fin plates. Each fin plate comprises a plurality of parallel adjacent straight banks. Each bank has the same width and comprises a plurality of convex portions and concave portions. The concave portions and convex portions are alternatively arranged. Each of the concave portions and convex portions has a U-like shape. Each of the convex portions and concave portions are opened at two ends. In assembly, adjacent banks are shifted with a predetermined length so that the convex portions and concave portions of the adjacent banks are not aligned and thus a portion between two adjacent portions of adjacent banks is opened. Thereby, a plurality of penetrating channels passing through a plurality of banks are formed along the openings of the concave portions and convex portions.