In this work, an effective method for controlling light emission of light-emitting diodes(LEDs) is proposed to maintain the light-emission characteristics. Wholly, there are two physical concepts of LEDs unutilized in this controlled method. One concept is the forward voltage and the junction temperature of LEDs could be described as a simple and linear relationship according to electric-thermal properties of LEDs. Thus the behavior on the junction temperature of LEDs could be monitored by a voltmeter in real time. The other concept is modulating the heat energy accumulated inside LEDs' junction by a heat dissipation module in real time. Therefore, with these physics concepts of LEDs, the effective method for controlling light emission of LEDs is implemented well by an aid of the feedback control mechanism. The results show the performance on the light-emission characteristics could be controlled to keep as a steady state, including optical power, peak wavelength and chromaticity under the feedback control mechanism.