To examine the enhanced heat dissipation effect of a crossed-fin heat sink on a 100W LED stage spotlight and optimize the design, we analyzed the main geometric factors and mechanisms that affect the heat dissipation performance of the heat sink. To this end, numerical simulation and experimental verification were performed. The optimization objectives were set as the highest temperature of the LED chip and mass of the heat sink. A single-factor analysis was performed on the length and spacing of the short fins, followed by a dual-objective optimization using the NSGA-Ⅱ algorithm. Fuzzy C-means clustering was then applied to obtain different heat sink configurations for different application scenarios. The results indicate that the crossedfin heat sink effectively enhanced the heat dissipation performance by increasing the average convective heat transfer coefficient of the fin surface. Both the length and spacing of the short fins exhibited optimal values that influenced the heat dissipation performance per unit mass. With excessively long short fins or excessively small spacing, the convective heat transfer coefficient on the fin surface decreased. After dual-objective optimization, the crossed-fin heat sink reduced the highest temperature of the LED chip by 2.33℃ with almost no change in its mass