An improved heat-dissipation structure includes a heat-dissipation lamp frame which comprises: a heat-dissipation structure and a plurality of heat-dissipation lamp sets. The heat-dissipation structure has a plurality of heat-dissipation fins on one side thereof, and the heat-dissipation lamp sets are accommodated on the other side of the heat-dissipation structure. An inlay slot is formed along the perimeter of the heat-dissipation lamp sets and is used to accommodate a light guiding tube which is a hollow and tube-like structure and has an inlay rim. The light guiding tube passes through the opening and is inlaid in the inlay slot of the heat-dissipation lamp frame. A casing is a metallic shell and has a through-hole on one side thereof to accept the heat-dissipation lamp frame. The casing has an opening on the other side thereof. A light-permeable cover is a light-permeable hood and has a contact plane on one side thereof.