Studies on NaCl concentration, pH tolerance and selectivity to different concent rations of Na +, K +, Mg 2+ and Ca 2+ of 43 isolates from th e saline soils in XinJiang, HeBei and QingHai Provinces of China and 4 type stra ins were performed in this paper Results showed that halotolerant actinomycete s have extensiv e adaptability to Na +, K + and Mg 2+ and only a few of them can grow in low CaCl 2 concentration Halophilic actinomycetes have extensive adaptability to Na +, and for most halophilic actinomycetes, Na + can be substituted by K + , Mg 2+ , but not for Ca 2+ For some halophilic actinomycetes , it is necessary to have Na + for their growth It also showed that the growth of al l halophilic actinomycetes had se lectivity with different concentration of Na +, K +, Mg 2+ So it is pre sumed that only Kaliumphilic or Magnesiumphilic Actinomycetes maybe exist in hig h salt environments In addition, the growth pH range were 6 0～9 0 and the o ptimum pH were 7 0～8 0 not only for halophilic but also for halotolerant acti nomycetes The dis tribution of halophilic actinomycetes also have some relativity to isolation sit es