Abstract:With four true leaves of Daphne giraldii Nitsche as the material, we investigated the effects of various NaCl stress(50,100,150 and 200 mmol·L-1)on photosynthetic physiological indexes as seedling photosynthetic pigment content, chlorophyll fluorescence parameters and gas exchange parameters of D. giraldii Nitsche. based on the pots experiments in sand culture systematically. The result showed that: (1) Under a proper environmental condition(Control), the daily variation of Pn and Gs are both illustrated by doublepeak curve while the daily variation of Tr is represented by a single peak one, thus the daily variation of D. giraldii Nitsche.’s leaves is changed by a higherconcentrated NaCl stress(>100 mmol·L-1) that causes an overall decline to the daily variation curves of Pn, Tr, as well as Gs, and an overall rise of Ci’s daily variation curve; (2) A lowerconcentrated NaCl stress(50 mmol·L-1) has little effects on the leaf chlorophyll content and the ratio of D. giraldii Nitsche and its chlorophyll content declined significantly by a higherconcentrated NaCl stress(>100 mmol·L-1)when the ratio had a slight decrease. (3)Fm,Fv/Fm, Fv′/ Fm′, qP, ΦPSⅡare all declined significantly by a higherconcentrated NaCl stress(>100 mmol·L-1), while F0 and NPQ are both raised significantly. The research shows that with the increasing of NaCl concentration, the reason for leading to the decrease of photosynthetic rate was mainly caused by the nostomatal factors; D. giraldii Nitsche is fairly resistible of less NaCl stress but a worse NaCl stress may damage the activity of photosynthetic apparatus, thereby surging photoinhibition and restricting photosynthesis.