The physiological and biochemical characteristics of Atriplex canescens seedlings under NaCl and Na₂SO₄ stress(0, 100, 200, 300 and 400 mmol·L^-1)was studied.The results shows that: (1) with the increase of salt concentration, the plant height, ground diameter and biomass increment were increased first and then decreased. Low salt concentration of the two kinds of salt promoted the growth of seedlings to some extent, when the concentration of salt reaches 400 mmol·L^-1, NaCl treatment inhibited the growth obviously. (2) Under the two kinds of salt treatments, the net photosynthetic rate and chlorophyll content of A. canescens seedlings increased with the increase of salt concentration, both of the two salts promoted the P_n rate and Chl content of seedlings, and the promotion degree of Na₂SO₄ was greater than that of NaCl. While the transpiration rate and stomatal conductance of A. canescens seedlings increased first and then decreased with the increase of the salt concentration, and the promotion degree of Na₂SO₄ was greater than that of NaCl. (3) Compared with the control, the malondialdehyde, SOD and POD of A. canescens seedlings were increased differently with the increase of the concentration of NaCl and Na₂SO₄ treatments, and the increase of NaCl treatment was greater than that of Na₂SO₄ treatment. The results showed that the resistance of A. canescens to Na₂SO₄ was stronger than that of NaCl.