Abstract: [Objective]In this study, Sinorhizobium populations were isolated from 14 different regions in Xinjiang,using Medicago sativa as trap host plants. [Method]A total of 81 rhizobial isolates were obtained and were confirmed that all of them fell into S. meliloti by PCR. [Result]Analysis of salt tolerance revealed that they can survive in YMA medium whose salt tolerance was between 3.5; to 5; NaCl, and there was no apparent correlation between salt tolerance in Sinorhizobium meliloti and the salt content of the soil samples.[Conclusion]The 16S rDNA sequence of 8 isolates,which had salt tolerance to 5; NaCl,were high,its similarity was high and reached 99.8;.The innolation test indicated that all the 8 isolates could increase the growth of aboveground part of alfalfa plant. Additionally, there is difference in the symbiotic nitrogen-fixing efficiency of these 8 isolates with alfalfa, and the nitrogen-fixing efficiency of TC-Y is higher than that of other isolates.