To study the resistant potential of Quercus variabilis seedlings under NaCl stress,we examined the biennial cork oak seedlings grown on containers with four soil NaCl concentrations (0%,0.4%,0.6% and 0.8%).Growth index and protective enzyme activities,proline content,root activity and other physiological indexes were systematically measured and analyzed under different stress conditions and at different stress time.Results showed that:(1)With NaCl stress increasing,fresh weight and dry weight of each organ,plant height and secondary root length all increased then decreased.But the mainroot length increased and the leaf number showed a gradual reduction.（2）With the extension of stress time,three protective enzyme (SOD,POD,CAT) activities were increased before decreasing,but the variation ranges were different.Malondialdehyde (MDA) content was increased,and it grew faster at higher stress level.(3)The organic substances for osmotic adjustment such as proline and soluble protein increased at the lower stress and then decreased at the higher stress;While the content of soluble sugar was continuously increased.(4)With the NaCl concentration rising,root activity increased and then decreased;Chlorophyll a and b both showed a downward trend.It was resulted that Q.variabilis seedlings improved the characteristic of resistance to soil salt stress by increasing the activities of protective enzymes and organic substances for osmotic adjustment in low and medium NaCl stress;Under severe NaCl stress,the metabolism in vivo and self regulation ability were in disorder and deprived,causing the protective enzyme activites,soluble protein content and root activity decreasing.