Compared with other lighting lamps,the thermal problem is still a bottleneck to limit the stability,reliability and lifetime of high-power LEDs.The thermal capabilities,including startup performance,temperature uniformity and thermal resistance of the loop heat pipe used on multi-chip high-power LEDs,under different heat loads and incline angles have been investigated experimentally.The obtained results indicate that the thermal resistance of the heat pipe heat sink is in the range of 0.48-1.47 K/W.The surface temperature difference of the evaporator is controlled nearly within 1.5 ℃ and 4.3 ℃ for 0°and 30° incline angle,respectively.Therefore,the impact of the incline angle of the evaporator on the heat transfer performance of the loop heat pipe should be assessed before such a structure of loop heat pipe is used to cool high-power LED system.