Abstract: In order to study the physiological mechanism of Quercus leaves during the color changing period in autumn and winter, four species of Ouercus: Quercus coccinea, Quercus nuttallii, Quercus shumardi, Quercus palustris, were investigated to determine the changes of chlorophyll, carotenoid, anthocyanin and soluble sugar, soluble protein in this period. Results showed that contents of chlorophyll a, b and a+b decreased obviously, which exhibited a quick decrease in the early stage and a slow decrease in the late stage. Variations of carotenoid in Quercus coccinea and Quercus shumardi first decreased, then increased and in the end decreased, whereas the other two species showed a smooth downward trend; the content of anthocyanin presented a trend of fluctuant rise. The changes of chlorophyll a/chlorophyll b were subdued at first and then decreased rapidly; the content of soluble sugar in Quercus coccinea presented a unimodal curve, while that of the other three species showed a bimodal curve with no significant correlation with anthocyanin. There was a positive correlation between the content of protein and anthocyanin.