Abstract: A system for automatically adjusting light intensity of a lighting fixture having multiple emitters, includes a power supply for supplying at least one current source to multiple emitters, at least one first emitter capable of emitting light of a first wavelength, at least one second emitter capable of emitting light of a second wavelength and a luminous intensity adjusting circuit for adjusting light intensity of the at least one first emitter. Particularly, the luminous intensity adjusting circuit stabilizes a first current distributed from a feeding current of the at least one current source and the multiple emitters collectively emit light at a predefined variable light-intensity.