Three-chips of light emitting diodes (LEDs) are flexible in spectrum composition,and the whole performance is easy to control.Through studying the range of luminous efficacy of radiation (LER),mesopic efficacy of radiation (MER) and circadian efficacy of radiation (CER) based on various combinations of threechips of LEDs,basic theories for spectrum optimization are provided.Three chips from six groups of single chip LED are chosen,which uniformly distributed on the chromatic diagram to fabricate three- chips of LED at different color temperatures of 2000 K,3000 K,4000 K,5000 K and 6000 K.ηLER,S/P ratio and acv value are calculated,and ranges of corresponding characters are achieved.Results show that ranges of corresponding ηLER ,S/P ratio and acv value are large,respectively reach 0.4,0.6 and over 0.4.Overall trends conform to former studies,high color temperature leads to high S/P ratio and acv value.But low color temperature LEDs may also reach moderately high S/P ratio and acv value,and high color temperature LEDs may also reach moderately low S/P ratio and acv value.Spectrum optimization of three-chips of LEDs effectively helps improving performance.