Abstract: To study NaCl stress on Syringa ‘Wedgewood Blue’ photosynthesis, we took 1-year-old seedlings of ‘Wedgewood Blue’ as test materials to study their photosynthesis, chlorophyll content and chlorophyll fluorescence under different concentrations of NaCl. The results showed that salt stress inhibited the photosynthesis. The chlorophyll content, qP, Φ_PSⅡ and Fv/Fm reduced with the increase of salt concentration, NPQ increased at first and then exhibited a decline. The main reason for photosynthesis reduction was stomatal limitation. The salt tolerance range of ‘Wedgewood Blue’ was below 0.4%. When the salt concentration was below 0.4%, the plant could improve the NPQ to resist the damage. When the salt concentration was higher than 0.4%, its photosynthetic organization was severely damaged, which resulted in serious photoinhibition.