The invention discloses a method for measuring the integral light decay property of an LED (
light emitting diode) lamp. The method comprises the following steps: firstly, selecting an 
LED lamp bead in the 
LED lamp as a to-be-tested device, secondly, putting the 
LED lamp into an 
incubator, disconnecting a circuit line between a driving 
power output and an 
LED array, connecting an 
ammeter in the circuit in series, and connecting a 
voltmeter to two sides of the to-be-tested device, thirdly, stabilizing the testing temperature in the 
incubator, taking the testing temperature as initial temperature T1, fourthly, turning on the LED lamp, and recording working 
voltage V1 and series current I1, fifthly, recording working 
voltage V2 and series current I2 at a stable 
thermal equilibrium state, sixthly, obtaining 
forward voltage difference 
Delta Vf, which is equal to V2 minus V1, seventhly, obtaining 
junction temperature difference 
Delta t, which is equal to 
Delta Vf / K, eighthly, obtaining 
junction temperature value T2, which is equal to T1 plus Delta t, and ninthly, looking up the light 
decay curve of an LED device, taking a cross axis reading in a position where a corresponding T2 decline curve and 70 percent of a normal axis are intersected as the service life of LED and also as the service life of the LED lamp at 70 percent of light decay.