A LED heat-dissipating downlight includes an enclosure body, a light source board, and a driving board. The enclosure body has a side opening. The accommodating chamber is substantially made of a heat dissipation material. The light source board and the driving board are disposed in the accommodating chamber. The light source board is disposed on a bottom of the accommodating chamber, and thermally contacted to the accommodating chamber. The driving board is disposed on the light source board. The driving board has a spacing hole, and the light generated by the light source board passes through the spacing hole to the side opening of the accommodating chamber.