Objective The aim of this investigation was to examine the changes of the color stability, surface microstructure and chemical constitution of light- curing composite resin after accelerated aging, and the relations between them. Methods Four light - curing composite resin were aged in an accelerated aging instrument. The color was measured by CIE L*a*b* with a spectrophotometer after treatment for 24 h and 96 h. And the color differences were calculated. Environmental scanning electron microscopy（ESEM） and Fourier transform infrared spectroscopy （FTIR） spectrometer were used to examine the microstructure and chemical composition of the specimens before and after accelerated aging. The color differences were analyzed statistically by repeated- measures two- way analysis of variance and t- test after aging for 24 h and 96 h. The level of significance was defined as α=0.05. Results The materials demonstrated statistically significant differences in color after aging between the 24 h and 96 h（P
