To ascertain the mechanism of ion osmosis adjustment adapted to saline soil habitat, we studied the absorption and distribution of the main mineral cations in roots, branches and leaves of E. moorcroftii trees with the age of one to twelve. Result showed that: (1) the Ca²⁺ accumulation of the tree was the highest (13.79 g/kg), K⁺ was the next (5.92 g/kg), Na⁺was the lowest (1.00 g/kg). With the increasing of tree age, the Na⁺ content in the roots, the K⁺, Ca²⁺ and Mg²⁺ contents in the branches and leaves had the rising trend, while K⁺ content had the opposite trend. The accumulation of Na⁺ in the root of the higher age grade trees were significantly bigger than that of the lower and middle age grade ones. (2) The K⁺/Na⁺ of the tree was higher (15.36) than the Mg²⁺/Na⁺ (12.25) and the Ca²⁺/Na⁺ (10.51). The K⁺/Na⁺ of the root and branch decreased, while it increased in the leaf. (3) With the increasing of tree age, the selective transport coefficients of K⁺ and Mg²⁺ from the soil to the root, and K⁺, Mg²⁺ and Ca²⁺ from root to branch, as well as K⁺ and Mg²⁺ from root to leaf showed the straight upward trend. (4) The Na⁺ content in the soil had an extreme significant positive correlation with the Na⁺ content in the root (0.687,P<0.01), and a significant positive correlation with the K⁺ content in the leaf (0.605 P<0.05). The K⁺ content in the soil had a significant and extreme significant positive correlation with the K⁺ in the leaf and Na⁺ in the root respectively (0.544, 0.676), and had a significant negative correlation with the Mg²⁺ in the root (-0.499). E. moorcroftii maintained the ion balance and adapted to saline soil habitat through accumulating Na⁺ in the root and selective absorpting the K⁺, Mg²⁺ and Ca²⁺ in the branch and leaf.