This paper proposes an original idea to minimize heat concentrations of high-power light-emitting diode (LED) arrays. The purpose of this paper is to investigate temperature distribution with and without an optimal process of high-power LED arrays by experiment and a numerical method in order to achieve an optimal design of LED arrays for thermal management. This paper develops an effective method to design each LED position for decreasing thermal concentrations in high-power LED arrays. In this paper, temperature profiles are measured by a thermal infrared camera and a thermocouple and compared with simulated results under different power. The optimal method is adopted by a simplified conjugate gradient method combined with a finite-element method. This method proves reliability of simulated results in advance. Through this optimal method, efficiency of heat removal will be enforced as an extra cooling device is added. The important part is that this optimal design will not affect brightness through an illumination analysis.