Abstract: A heat dissipation device includes a heat conductive member, a fin unit coupled to a bottom surface of the heat conductive member and a plurality of LED modules attached to a top surface of the heat conductive member. The heat conductive member consists of a first plate, a second plate parallel to the first plate and a plurality of posts sandwiched between the first and second plates. Peripheries of the first and second plate are in a hermetical conjunction with each other to form a chamber containing a phase-changeable working fluid therein. The first and second plates therein define a plurality of through orifices. The posts each define therein a screwed orifice which is in alignment with corresponding through orifices of the first and second plates respectively and threadedly receives a screw extending through the LED module.