A heat dissipation device (20) includes a plurality of individual fin plates (40) arranged side by side. Each fin plate includes a main body (42). First and second flanges (44, 46) extend perpendicularly from opposite edges of the main body of each fin plate. A pair of tongues (48) is stamped perpendicularly from the main body and is opposite to the first flange. A pair of projections (49) is stamped from the main body adjacent and opposite to the second flange. Protrusions (442) are formed at the first flange and holes (482) are defined in the tongues respectively. The tabs of a first fin plate are interlocked with the projections of an adjacent second fin plate. The protrusions of the first fin plate are received in the holes of the second fin plate. In similar fashion, all the fin plates are assembled together. The heat dissipation device is thus formed.