本研究利用形狀因子(Shape factor)為基礎，搭配有限元素分析(FEA)模擬軟體建立三維軸對稱模型，並整理出其形狀因子與幾何形狀之關係圖，經數學式擬合後建立快速熱阻估算法，快速熱阻估算法不僅可應用於軸對稱式結構之熱阻計算，更可應用於複合式結構、方形結構與非對稱式結構等熱阻計算，最後搭配模擬退火法優化一實際燈具之熱阻。快速熱阻估算法不僅可以有效且迅速的估算物體之熱阻，也可大幅減少燈具設計階段之時間、人力與金錢的消耗。;In this research, shape factor is regarded as basis and finite element analysis (FEA) software is used to build the three-dimensional axisymmetric model, and then find the figure related to shape factor and geometric shape. After fitting the curve of figure, the rapid estimation of thermal resistance method is built. The rapid estimation of thermal resistance method can apply to not only axisymmetric structures but also composite structures, square structures and asymmetric structures. Finally, the thermal resistance of an actual LED thermal module will be optimized by simulated annealing. The rapid estimation of thermal resistance method cam not only estimate the thermal resistance of the sample effectively and rapidly but also reduce the time, manpower and money during the period of design.