A heat dissipation device includes a retention module (40) and a heat sink (10) both mounted on the printed circuit board (50). The retention module forms a pair of opposite fixture blocks (44) thereon. The heat sink received in the retention module has protective hollow sleeves (28) positioned corresponding to the blocks. Each sleeve has a supporting pad (286) therein. A pair of braces (32) each extend through the sleeve and comprise a baffle portion (321) located above the pad and a fastening portion (324) below a bottom end of the sleeve. A spring (33) is compressed between the baffle portion of the brace and the pad of each of the sleeves. The fastening portions of the braces securely fasten the blocks of the retention module after the first springs are stretched a distance with an upward movement of the braces.