The invention discloses a iunction temperature measurement method for an LED lamp. The junction temperature measurement method for the LED lamp comprises steps of loading a current pulse in an LED light source; collecting an LED instantaneous junction voltage response; measuring the junction voltage response of the LED at different temperatures, and completing the V-t calibration of the LED light source; and measuring the current value and the voltage value of the LED light source in the actual operation of the LED lamp to calculate the junction temperature of the LED lamp. The junction temperature measurement method for the LED lamp provided by the invention can measure the junction temperature of the LED lamp, and avoid the influences on the junction temperature of the difference of the processing technology, the difference between the whole package, and change of the actual working environment and the internal drive circuit output.