Abstract: The morphological characteristics, physiological indexes and mineral elements were investigated with seedlings of Euonymus alantus, Elaeagnus angustifolia and Fraxinus Americana. The seedlings were cultivated in pots that were treated with different NaCl concentrations. The results showed: Under salt stress, the relative height growth and biomass inhibited. The chlorophyll content decreased with increase of the salt concentration. The membrane permeability, MDA, SOD, proline and soluble sugar content of salt-stressed plants increased as the salt concentration increased. Under the salt stress, the Na⁺ content of the roots, stems and leaves of plants increased gradually, while the change pattern of K⁺ content was different. The K⁺ content in roots decreased with the NaCl concentration increased, it in stems had no significant changes, and it in leaves of 3 tree species had differential changes. Salt tolerance of the 3 tree species was comprehensively evaluated with correlation analysis, principal component analysis and subordinative function. The sequence of salt tolerance of the 3 tree species from strong to weak was: E. alantus > E. angustifolia > F. americana. This result was coincided with the sequence ranked in terms of symptoms of salt injury. Screening identification indexes was studied by gray correlation analysis and the results showed that the relative height growth, membrane permeability, proline, Na⁺ and K⁺ contents were important indexes for evaluating salt tolerance of the species.

Key words: salt stress, salt tolerance, comprehensive evaluation, screening identification indexes