Abstract: The effect of salinity stress on the germination rate of tree seed show that the two kinds of salts(NaC1 and NaCl+KC1)both have harmful influence on the seed germination as well as seedling growth．With the salinity concentration rising．the germination rates fal1 and the seedling growing worsen．Additionally compared with the compound Salts(NaCl+KCl)，single salt(NaC1)is stronger to hinder the seed germination and seedling growth，which indicates that K⁺ can alleviate the negative effect of Na⁺.Finally，the concept of index of salinity tolerance is put forward．