In order to clarify the effects of different concentrations of NaCl stress on the biomass,photosynthesis and chlorophyll fluorescence characteristics of blueberry seedling,this paper performed 50 d simulated NaCl stress pot experiment at the four salinity gradients of 50 mmol·L^-1,100 mmol·L^-1,150 mmol·L^-1 and 200 mmol·L^-1,using 2-year-old Vaccinium corymbosum L.‘Bluecrop’ seedlings as the materials and using the seedlings without NaCl stress as the control(CK).The results showed that:(1)the aboveground fresh mass and belowground of blueberry seedling were no difference with the control when the NaCl concentration was 50 mmol·L^-1,but were significantly decreased when the NaCl concentration was greater than 100 mmol·L^-1;the aboveground biomass,belowground biomass and total biomass of blueberry seedling were no difference with the control when the NaCl concentration was below 100 mmol·L^-1,but were significantly decreased when the NaCl concentration was greater than 150 mmol·L^-1;the root/shoot ratio of blueberry seedlings were no difference with the control under NaCl stress;(2)When the NaCl concentration was greater than 150 mmol·L^-1,the Chl a,Chl b and Chl contents in leaves of blueberry seedling were significantly reduced;(3)The net photosynthetic rates(P_n),transpiration rate(T_r),and stomatal conductance(G_s) in leaves of blueberry seedling were no difference with the control when the NaCl concentration was 50 mmol·L^-1,but were significantly decreased when the NaCl concentration was greater than 100 mmol·L^-1.The intercellular CO₂ concentration(C_i) and stomatal limiting value(L_s) were significantly decreased under NaCl stress at 200 mmol·L^-1;(4)Dark-adapted maximum fluorescence(F_m),maximum photochemical efficiency(F_v/F_m),potential photochemical efficiency(F_v/F₀),PSⅡ quantum yield(Φ_PSⅡ),photosynthetic electron transport rate(ET) and photochemical quenching coefficient(q_P) were no difference with the control when the NaCl concentration was below 150 mmol·L^-1,but were significantly decreased when the NaCl concentration reached 200 mmol·L^-1.These results showed that blueberry seedling had a certain ability to adapt NaCl stress,which could withstand 100 mmol·L^-1 NaCl concentration,while the decrease of P_n under high NaCl concentrations was due to both stomatal and non-stomatal factors.High concentration of NaCl treatments caused certain damage to photosynthetic systems.The contents of chloroplyll were significantly reduced.The reduction in electron transport flow induced photoinhibition,ultimately reducing the photosynthetic rate and the decline in biomass.