The photosynthetic characteristics of Quercus acutissima from Feixian, Chuzhou and Wanyuan provenances were investigated under NaCl stress at 5 concentrations. For the three provenances, their leaf chlorophyll a (Chl a) and chlorophyll b (Chl b) contents and net photosynthetic rate (Pn) decreased with increasing salt stress, among which, the maximal decrement of Chl a content was 21.5%-36.1% for Feixian provenance, and 3.5%-19.8% for Wanyuan provenance. The diurnal variation of Pn, in control groups had a single peak, and no midday photosynthetic depression was observed. Under high salt stress, all the provenances presented midday photosynthetic depression. Path analysis indicated that the major factors affecting Pn were vapor pressure deficit (VPD) and leaf temperature (Tl) , while the minor factors were stomatal conductance (Gs) , intercellular CO2 concentration (Ci), and photosynthetically active radiation (PARi). In the control groups, the photosynthetic characteristics mainly depended on the climate factors of provenance location. Based on the variations of leaf chlorophyll contents and Pn among the provenances under different salt stress, Wanyuan provenance had the highest salt tolerance, followed by Chuzhou provenance, and Feixian provenance.