Abstract: In order to get the response mechanism of Suaeda glauca and Atriplex triangularis to different salinity level, we investigated the alteration of different concentrations of NaCl with Hoagland solution on plant biomass, height, water content (WC), chlorophyll (Chl) content, carotenoid (Car) content, Chl/Car, Chl a/Chl b, Pn, Gs, Ci, Tr, water use efficiency (WUE) and stomatal limitation (Ls) in S. glauca and A. triangularis seedlings in this study. 1) Compared with control, treatment with 100 mmol/L NaCl significantly increased the dry weight, height and shoot WC of S. glauca plant, however, 100 mmol/L NaCl did not affect the plant height of A. triangularis, decreasing its shoot dry weight and WC markedly. Treatment with 400 mmol/L NaCl had no effect on the shoot dry weight (DW) and WC of S. glauca, but it heavily reduced shoot DW and WC of A. triangularis. With salinity of 800 mmol/L NaCl, DW and WC of two plants were decreased significantly, and the decrease of A. triangularis was much more than that of S. glauca. 2) Treatment of 100 mmol/L NaCl did not affect the Chl content, and treatments of 200 and 400 mmol/L NaCl significantly decreased the Chl content in both two plants. However, the decrease was much more significantly in S. glauca than that in A. triangularis under 200 and 400 mmol/L NaCl. Treatment of 100 mmol/L NaCl significantly increased the Car content of S. glauca, but did not affect the Car content of A. triangularis. Treatments of 200 and 400 mmol/L NaCl significantly decreased the Chl content in both two plants. Similarly, the decrease was much more significantly in S. glauca than that in A. triangularis. All NaCl treatments did not affect Chl a/Chl b in both plants and Chl/Car in A. triangularis, but Chl/Car in S. glauca was descended in first and ascended at last as NaCl concentrations rising. 3) We found that values of Pn, Gs and Tr in S. glauca were all ascended under treatment with 100 mmol/L NaCl, while 100 mmol/L NaCl significantly decreased the Pn, Gs and Tr in A. triangularis. Under stresses of 200 and 400 mmol/L NaCl, Pn, Gs and Tr were significantly decreased in both two plants. However, Pn and Tr were decreased more significantly in A. triangularis than in S. glauca. With the increase of salinity, the Ci value in S. glauca was gradually decreased. Meanwhile, in A. triangularis, the Ci value was descended in first and then ascended, and Ci in the treatment of 800 mmol/L NaCl was obviously higher than that in the control. 4) Biomass of S. glauca showed highly significant positive-correlation with its Tr, Pn, shoot WC, Car content, root WC, Gs, root shoot ratio, plant height, Chl content and Ci, and showed highly significant negative-correlation with its Chl/Car and Ls. For A. triangularis, its biomass was highly significant positive-correlation with shoot WC, Chl content, Pn, Car content, Tr, Gs, root WC and plant height, but highly significant negative-correlation with Chl a/Chl b. To sum up, S. glauca and A. triangularis both have high salt resistance. Compared with A. triangularis, S. glauca having better adaptation to salt was owing to maintaining higher photosynthetic and water use efficiency. Under severe salt stress, the reduction in photosynthesis of S. glauca was mainly due to stomatal limitations, while for A. triangularis, the reduction in its photosynthesis was mainly due to non-stomatal limitations.