In order to analyze the physiological response difference of Lycium barbarum to mixed salt (NaCl+Na₂SO₄), we selected one year seedling of ‘Ningqi No.5’ and ‘Heiqi No.1’ as the materials, with different salinity treatments under different osmotic potential gradients (-0.47, -0.82 and -1.18 MPa, respectively). The results showed that: (1) with the decreasing of osmotic potential, chlorophyll (Chl) and soluble protein (SP) contents increased firstly and then decreased. The relative conductivity, malondialdehyde (MDA), proline (Pro) and soluble sugar (SS) contents gradually increased, but ‘Ningqi No.5’ trend is greater than ‘Heiqi No.1’. (2) The activities of antioxidant enzyme superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased, while the osmotic potential of -1.18 MPa inhibited the activities of antioxidant enzymes in ‘Ningqi No.5’. (3) With the prolongation of treatment time, MDA, Pro and SS contents and CAT activity increased in two kinds of L. barbarum，and the accumulation of ‘Ningqi No.5’ is higher than that of ‘Heiqi No.1’; while the content of Chl and the activities of SOD and POD decreased at -1.18 MPa. All these results suggested that both types of L. barbarum can relieve salt stress by accumulating osmotic regulating substances and strengthening the antioxidant enzyme system. ‘Ningqi No.5’ has stronger osmotic adjustment ability, while ‘Heiqi No.1’ has a more stable antioxidant enzyme system and thus has a stronger ability to tolerate salt stress.