a plurality of fins; an upper side and a lower side of each fin being folded with folding sheets; each of two sides of each sheet being protruded with a buckling ear; the buckling ear being formed by a triangular sheet and a support plate; the support plate being connected to one apex of the triangular sheet and the folding sheet; a hole being formed on the folding sheet and being located behind the buckling ear; the shape of the hole being corresponding to that of the buckling ear; a tenon being formed at two lateral walls of the hole and a middle section of the tenon being protruded with a semi-round section;

wherein in assembly, the buckling ears of one fin are buckled to the holes of another fin so as to assembly two fins together; the tenon serves to buckle the buckling ear to the hole; more fins are assembled by the same way; the heat dissipating device can be assembled to a computer central processing unit.