The temperature of junction in LED affects the life time and performance. however, the measurement of junction temperature in module is very difficult. In this paper, to measure the junction temperature in LED module, optical and electrical properties is measured in single package in temperature from 25 [℃] to 85 [℃], and then junction temperature can is estimated in module with measuring the average voltage of single package. As results, the junction temperature of single package is measured the temperature of 61.2 [℃] in ambient temperature, also, the junction temperature of LED module is measured the temperature of 72.5 [℃] in ambient temperature.
