The soil cultivation experiment was used to investigate the effects of uranium on the photosynthetic characteristics of spinach(Spinacia oleracea L.) leaves.Spinach seedlings of the six-leaf stage were treated with different concentrations of uranium [UO₂(CH₃CO₂)₂·2H₂O](0,20,50,100,150 mg·kg^-1),and photosynthetic pigment content,photosynthetic gas exchange parameters,chlorophyll fluorescence parameters of leaves,growth indexes were investigated after 7,14,21 and 28 days of uranium treatment,respectively.The results showed that:(1)compared with the control,the chlorophyll content,net photosynthesis (P_n),stomatal conductance (G_s),transpiration rate (T_r) were significantly improved by low uranium concentration (20,50 mg·kg^-1),after that with the increase of uranium concentration all of the parameters significantly decreased,and along with elevated levels of uranium as well as the duration of treatment,all the parameters then decreased significantly compared with the control while intercellular CO₂ concentration (C_i) was getting rise.It showed that the decline of P_n was caused by nonstomatal factors.(2)High uranium concentration obviously influenced on the chlorophyll fluorescence parameters of plant leaves.PhotosystemⅡ (PSⅡ) maximum fluorescence (F_m),PSⅡ maximum photochemical efficiency (F_v/F_m),PSⅡ potential activity (F_v/F₀),declined obviously,while minimum fluorescence (F₀) were obviously rise.(3)Root length,plant height and biomass showed a obvious rise under low concentrations of uranium treatments,and a decline under high concentration(100,150 mg·kg^-1) uranium treatments.Thus,low uranium concentration could improve photosynthetic function of spinach seedlings and increase photosynthetic efficiency,but a high concentration can harm the photosynthetic apparatus and inhibit photosynthetic efficiency.