The heat dissipation device for a LED lamp contains an upper piece, at least a lower piece, and a number of heat dissipation elements. The upper piece has a number of first, second, and third plug holes. The second plug holes are aligned with some first plug holes, and they are connected by conductive layers. The other first plug holes are connected by separate conductive layers. The third plug holes are configured on individual conductive layers. A number of LEDs have their leads threaded through the first plug holes, respectively. The heat dissipation elements have their two ends threaded through a second plug hole and a third plug hole, respectively. The leads and the heat dissipation elements are then soldered to their respective conductive layers. A number of tubular sleeves are sandwiched between the upper and lower pieces and the leads of the LEDs are threaded through the tubular sleeves.