Abstract: The tissue culture seedlings of Acer rubrum were used as experimental materials, and the complex saline-alkali stress (four single salts were NaCl, Na₂SO₄, NaHCO₃, Na₂CO₃) and Na ⁺ concentration of 32 mmol/L were used as stress conditions. By setting different concentrations of trehalose solution (0, 5, 10, 20, 30 mmol/L),the effects of complex saline-alkali stress on the physiological indexes and ion content of Acer rubrum seedlings were investigated, and the optimal trehalose concentration that could alleviate the combined saline-alkali stress was screened by grey correlation analysis.The results showed that under compound salt alkali stress conditions, with the increase of trehalose concentration, the contents of chlorophyll a, chlorophyll b, carotenoids, and intracellular antioxidant enzyme activities (SOD, POD, CAT) showed a trend of first increasing and then decreasing; Osmotic regulating substances (soluble sugars, soluble proteins, free proline), non enzyme antioxidants such as reduced glutathione (GSH) and ascorbic acid (AsA) also showed a trend of first increasing and then decreasing; The activity of ascorbate peroxidase (APX), oxidized glutathione (GSSH), and dehydroascorbic acid (DHA) content first decreased and then increased; The content of secondary metabolites (flavonoids, total phenols, anthocyanins, lignin) showed a trend of first increasing and then decreasing; Exogenous trehalose significantly reduced the Na ⁺ content in the leaves of American maple seedlings and increased the plant's absorption of K ⁺ . Through comprehensive salt alkali tolerance analysis, the results of grey relational analysis show that the application of 10 mmol/L trehalose can significantly improve the resistance of American red maple seedlings to compound salt alkali stress.