Caesalpinia sappan (sappan) is a commonly used ancient red vegetable dye. With the aim of protecting sappan wood dyed silk, the effect of light on fading was investigated by light aging tests.The lamps tested are those commonly used in museums, and include LED, fluorescent and halogen lamps. To evaluate the effects of both light and other environmental factors, a discoloration factor index system is established. The results show that the discoloration effect of LED lamps is greater than the effects of conventional halogen and fluorescent lamps; the discoloration effect of low color temperature is slightly less than that for high color temperature lighting; also the higher the illuminance, the bigger the discoloration effect.Other environmental factors also have a great influence on discoloration. The use of suitable halogen,or low color temperature fluorescent lamps and LED lighting for Caesalpinia sappan dyed silk showcases.The level of illumination of showcase lighting should be controlled. Meanwhile, other environmental factors in showcase can not be ignored.