根据LED的电压与结温的线性关系，对其施加不产生加热效应的脉冲电流，并通过调节热沉温度，使脉冲下的正向电压与直流下电压相同，从而得到结温及直流下结到热沉的温差，同时可测量光学、电学等参数，进而达到测量热阻的目的。用不同脉宽，不同偏置电流的脉冲进行测量，并与传统电学法热阻测试结果比较了测量结果的差异，分析了产生差异的原因。此方法可在控制结温的情况下精确测量LED的光学、电学、色度学和热学参数，对正确评价LED性能有着指导意义。

According to the linear relationship of forward voltage and junction temperature, a pulse current, which doesn't result in heating effect, was applied on LED to test the junction temperature and the temperature difference between junction and heat sink by controlling the heat sink temperature so that the forward voltage under the pulse current is equal to that under DC mode. Meanwhile the optical and electrical parameters were also measured, so the thermal resistance could be deduced. Pulse currents with different pulse widths and bias currents were adopted to discuss the differences between the pulse method and the traditional electrical method for thermal resistance. Based on the direct and accurate junction temperature control, the measurement of the optical and electrical parameters offers valuable evaluation of power LED.