In this paper, two year seedlings of important economic tree species (Lycium barbarum) in the inland high cold region was studied. We conducted a pot experiment to study the effects of 50,100,200 and 300 mmol·L^-1 salt and alkali (NaCl and NaHCO₃) treatments on growth physiological and photosynthesis of L. barbarum seedlings. The salt and alkali tolerance threshold were determined by analyzing the parameters, and the relationship between soil salinity and soil moisture content was constructed based on this, which provided theoretical basis for the planting and management of wolfberry in different types of saline soil. In this study, (1) with the increasing of critical concentration, the biomass, chlorophyll content (SPAD), net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), intercellular carbon dioxide concentration (C_i) were significantly inhibited and the alkalistress was stronger. However low concentration (50 mmol/L) of NaCl did not significantly inhabit the contents of SPAD and Pn of L. barbarum seedlings. (2) The Pn_max, RD, AQY and LSP under salt and alkali stress were lower than that of CK, but the LCP was higher than that of control group. (3) With the increasing of the stress concentration, the variation under alkali stress was greater than that under salt stress. The critical values of stomatal and nonstomatal limitation were analyzed by the change rule of C_i. 200 mmol/L and 100 mmol/L were the change critical values under saltstress and alkalistress, respectively. (4) The salt and alkali tolerance threshold of L. barbarum were (246.3±2.1) mmol/L and (126.7±2.7) mmol/L, respectively. On the basis of this threshold, the regression curves of soil water content and soil salinity were obtained. The research suggests that, the seedling of L. barbarum has a certain salt tolerance ability, but a high salts concentration can damage the photosynthetic structure and reduce the light adaptability and photosynthetic efficiency. These results would provide some reference for L. barbarum production and irrigation in saline land.