This article explored the effect of natural light and ultraviolet lamp radiation on the discoloration of the green part of the 4-year bamboo by using the color analyzer and Fourier transform infrared spectrometer. The results showed that both light treatment could make the discoloration of the bamboos green part obviously, and the lightness increased, the color hue (a*) changed a little, however, the color hue (b*) had a great change, and the aberration(Delta E*) increased with the increasing duration. FTIR results showed that the chemical structure of the bamboos green part had a change, and the components of the lignin decreased because of the degradation, but the hydroxyl increased.