To design the heat sink of liquid cooling system effectively and improve the comprehensive performance of heat transfer for high power LEDs, the LED maximum temperature and thermal resistance of three types of heat sinks are numerically investigated. The mechanism of heat transfer is analyzed by using the field synergy principle, and the variation of the Nusselt number and friction factor are examined with Reynolds number. And using the thermal enhancement factor to express the comprehensive performance of heat transfer between the heat transfer performance and flow resistance. The results show that the LED maximum temperature and thermal resistance using the rectangular fin with the inclined angle of 30° is lowest, the heat transfer enhancement is highest, and rhombic fin is followed, vertical parallel fin is worst. The rectangular fin with the inclined angle of 30° and rhombic fin have the higher flow resistance when they have the higher heat transfer performance, because of the oblique angle. Considering the heat transfer performance and flow resistance, rhombic fin has the highest comprehensive performance of heat transfer.