To understand the salt tolerance mechanism of Nitraria sibirica seedlings under NaCl treatment, we investigated the growth of oneyear old N. sibirica seedlings and cationic absorption and distribution in different organs (such as roots, stems and leaves) under different levels of NaCl (0, 200 and 400 mmol·L^-1) treatment through hydroponic experiment in greenhouse. The results showed that: (1) the N. sibirica seedlings growth and succulent degree of leaves were significantly increased by 200 mmol·L^-1 NaCl treatment compared with control, but that were inhibited by 400 mmol·L^-1 NaCl treatment. (2) With the increase of NaCl concentration, the Na⁺ content in the roots, stems and leaves of the N. sibirica seedlings were significantly increased compared with those of the control seedlings, and the Na⁺ content in the leaves was significantly higher than that in stems and roots; The content of K⁺ in roots was significantly increased with the increase of NaCl concentration; The contents of Ca²⁺ and Mg²⁺ in roots, stems and leaves were stay steady or rise under 200 mmol·L^-1 NaCl treatment whereas decreased under 400 mmol·L^-1 NaCl treatment. (3) With the increase of NaCl concentration, the K⁺/Na⁺, Ca²⁺/Na⁺, Mg²⁺/Na⁺ ratios in different organs of seedlings were decreased, and the ratio of roots was always higher than that of stems and leaves. (4) The ability of K⁺ transporting from roots to stems was significantly decreased whereas the abilities of Ca²⁺, Mg²⁺ transporting from roots to stems and the abilities of K⁺, Ca²⁺ and Mg²⁺ transporting from stems to leaves were decreased under NaCl treatment. In conclusion, our findings suggested that the saltadaptation mechanism of N. sibirica seedlings were primarily implemented by plant compensation growth effect, leaf Na⁺ accumulation, also correlated with the ability of root arrest K⁺ and increased abilities of K⁺, Ca²⁺ and Mg²⁺ selective transportation in stems and leaves.