Heat transfer characteristics of a high-power light-emitting diode (HPLED) have been carried out in terms of experiment and simulation. Finite volume method was used to analyze the temperature and thermal stress distributions in the HPLED package as a function of drive current and package structure. Predicted temperatures of silicone encapsulant and epoxy resin showed a good agreement with measured temperatures. The thermal stress increased with the drive current due to a heat burden. The intersection edges between the light emitting diode chip and the silicone encapsulant showed a higher thermal stress. The thermal stress of Cu-thin-film coated package was lower than that of other package structures because of an efficient cooling effect.