Abstract: The variations of chlorophyll content and some osmotic adjustment substances such as proline, soluble sugar and protein in leaves of Betula microphylla under Na₂SO₄ and NaCl stress were investigated. The results showed that the variation pattern of physiological characteristics under NaCl stress was same as that under Na₂SO₄ stress: the chlorophyll content decreased gradually; the contents of proline and soluble sugar increased significantly with the increment of salt concentration; the protein content decreased at first and then increased later under weaker Na⁺ stress; the protein content decreased gradually under stronger NaCl stress. An intensive change of these physiological characteristics was found under NaCl stress, suggesting that the injuries imposed by NaCl stress was greater than that by Na₂SO₄ stress, B. microphylla might partially adopt to SO^2-₄ due to long-term survival under their natural habitat.