Abstract: By adding lower concentration(10 %) and higher concentration(20 %) of PEG6000 into Hoagland solution to simulate different gradient drought stresses, the relative water content, water potential, relative penetrability of cell membrane, the proline content, the chlorophyll content and the ratio of chlorophyll a and b and chlorophyll fluorescence in leaves of Quercus virginiana were investigated. The results showed that when treated with lower concentration(10 %)of PEG, the water potential and the relative rate of electron transport(rETR) decreased with the proline content, relative conductivity, malondialdehyde(MDA) content, nonphotochemical quenching（NPQ）and the rate of thermal dissipation （Drate）increased significantly（p<0.05）, while the coefficient of photochemical quenching(qP), the rate of photochemical reaction（Prate）and relative limit of photosynthesis （LPFD）changed slightly. Whereas the concentration of PEG was increased to 20 %, qP and Prate decreased significantly（p<0.05）, the MDA content, relative conductivity, NPQ and Drate had a sustained increase,while the water potential decreased and the proline content increased more significantly. The relative water content, the minimal fluorescence (Fo), the maximal fluorescence (Fm), maximal quantum yield of PSⅡ（Fv/Fm）,the potential activities of PSⅡ(Fv／Fo) and actual photochemical efficiency of PSⅡ（ΦPSⅡ）were almost unaltered under both lower and higher concentration of PEG, which indicated there may be a better waterholding capacity in leaves of Q. virginiana when exposed to drought stress. Moreover, the photosynthetic apparatus could keep stable activity by moderately thermal dissipation mechanism in leaves of Q. virginiana, which could be considered as an adaption of Q. virginina to drought sress.