Abstract: The adaptation mechanism of malting barley (Hordeum vulgare) growth response and ion distribution elicited by extended exposure to NaCl stress were investigated by simulating the formation process of soil salinisation in arid and semi-arid irrigated regions. The objective was to provide the theoretical basis for increasing the yield of malting barley and rationally employing the salt-affected arable land in irrigated agricultural systems. Seedlings of malting barley were treated by adding NaCl to the growth medium to gradually increase the concentration in 17.1 mmol/L increment every week during the vegetative period until a concentration of 154.9 mmol/L was reached. Nine harvests (7 d after treatment) were analysed to examine plant growth, root growth parameters, ion contents, and photosynthetic characteristics. The growth rate of barley seedlings was inhibited by extended exposure to NaCl. Under salinity stress the shoot biomass and height decreased significantly in comparison with the control, but the root biomass and root/shoot ratio increased significantly with extended exposure to NaCl. In addition, root length increased at lower salt concentrations with a short incubation period. At higher NaCl concentrations (≥85.5 mmol/L NaCl), salt stress seriously inhibited the growth of the seedlings and the water content of malting barley was seriously decreased. Furthermore, with an increase in salt stress level, photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ concentration (C_i) and transpiration rate (T_r) were significantly reduced. This was strongly dependent on the appearance of non-stomatal limitation to photosynthetic characteristics imposed by long-term induced salinity stress. Under extended exposure to NaCl stress, Na⁺ and Cl^- content in shoots increased significantly, whereas in roots, Na⁺ content increased but Cl^- content decreased with the extension of incubation days. Compared with the controls, the K⁺/Na⁺ in shoots significantly decreased as NaCl concentration increased. Malting barley accumulated much more Na⁺ in shoots by selectively absorbing K⁺ under intense salt stress. The selective absorption and transportation of K⁺ were the key adaptive mechanism of high salt-tolerance of malting barley.