The plastic response of Bassia dasyphylla (Fisch. & C.A. Mey.) Kuntze functional traits to saline-alkali land habitat and its mechanism were investigated. Two neutral salts, NaCl and Na2SO4, and two alkalisalts, Na2CO3 and NaHCO3, were mixed in various ratios according to the varying ranges of salinity and pHin a natural soil, and the response of B. dasyphylla seedlings to salt-alkaline stress was determined. Theosmolyte contents, peroxidative damage, antioxidant enzyme activity and plant morphology and biomasswere determined. Thirty different salt-alkaline ecological treatments were applied, including ranges of salin-ity of 50-250 mmol/L and pH values of 7.10-10.19. The soluble sugar, soluble protein, proline, betaine,hydrogen peroxide and malondialdehyde contents, production rate and cell membrane permeability ofB. dasyphylla rose with increases in salt concentration and pH. There were differences between the treatmentgroups and the control (P < 0.05). The activities of superoxide dismutase, peroxidase and ascorbate peroxi-dase enzymes initially increased and then decreased, but catalase activity continued to increase. The plantheight, main root length, stem thickness, branch number, lateral root number and root, stem and leaf biomasswere significantly decreased compared with the control (P < 0.05). In regard to biomass, the proportion ofroot biomass increased, but the proportions of stem and leaf biomass decreased. The correlations between thesalt component ions and the above plant characteristics indicated complex effects of salt composition on thefunctional characteristics of B. dasyphylla. This study suggests that salt-alkaline environments inhibited thefunctional characteristics of B. dasyphylla and negatively affected several physiological responses and mor-phological plasticity.