A heat dissipation structure of an SMD LED includes a substrate, an SMD LED and at least one engaging member. A plurality of conductive copper foils is covered on an upper end face of the substrate. Two electrodes are provided on a lower surface of the SMD LED and are respectively connected to two copper foils on the upper end face. An engaging hole extends through one of the copper foils adjacent the SMD LED and through the substrate. The engaging member is made of high thermal conductive metal and is engaged in the engaging hole to combine the copper foil and the substrate. Accordingly, heat generated by the SMD LED can be directly transferred to an exposed lower end face of the substrate through the engaging member for more heat dissipation and less luminance decrease of the SMD LED.