The present invention provides a method for producing high-quality light, wherein this high-quality light producing method consists of a plurality of particularly-designed process steps based on the sensitivity of human eyes and the melatonin suppression. So that, research and development engineers of lighting devices are able to manufacture a high-quality lighting unit or module through this novel method. Moreover, a variety of experimental data have proved that, the high-quality lighting unit produced by using this novel method is able to perform the advantages of high SRI (Spectrum Resemblance Index) and low MLT (Melatonin) suppression rate.