Abstract: In order to investigate the effects of extractives on photo-degradation of thermally-modified wood during artificial weathering, different kinds of extracted thermally-modified and unmodified wood samples were exposed in a xenon weatherometer for 1008 h and then the surface color and chemical changes were tested by chromameter, scanning electron microscope (SEM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT-IR) and X-ray photoelectron spectroscopy (XPS), respectively. The results showed that:1) The existence of polar extractives with low molecular weight could release the photodegradation of thermally-modified wood, but could not prevent the degradation of lignin and the formation of carbonyl derivatives during weathering; 2) Alkali extractive influenced the color of beech wood most significantly and slowed the color change during weathering. Polar substances that were extracted with benzene-ethanol and water showed positive effects for improving the color stability of thermally-modified beech. Exfoliation of wood ray cells occurred in water extracted thermally-modified beech; 3) The color change of thermally-modified Scots pine was more obvious than beech wood during weathering because original color of Scots pine was slighter than beech wood. The effect of alkali extractives on color stability of thermally-modified Scots pine was not significant, while benzene-ethanol and water extractives improved the anti-weathering property of Scots pine significantly.