The diversity and phylogeny of 86 rhizobial strains which isolated from the root nodules of Lespedeza Michx in arid-hot valley of JinSha river in Sichuan, China, were studied by numerical taxonomy,BOXAIR-PCR fingerprinting,16S rDNA PCR-RFLP, 16S rDNA and GSⅡ sequences. The result of numerical taxonomy showed that there was a great phenotypic diversity among the isolates. The strains tested could grow normally at 60℃ or pH＜4.0 culture conditions. However, they could not grow at 10℃ or pH＞9.0. They were not endured salt tolerance. The same strains used in numerical taxonomy were analyzed by 16S rDNA PCR-RFLP with four kinds of restriction endonucleases (HaeⅢ、MspⅠ、HinfⅠand TaqⅠ). The strains had 16 genotypes and 10 unique genotypes different from the reference strains. Based on the dendrograms generated by BOX-PCR, the strains were divided into 37 groups at the similarity of 82%, some strains belonged to one phenon in 16S rDNA PCR-RFLP are in different phenons in BOXAIR-PCR, which showed that there was a great diversity in genes among the stains. The results of analysis on 16S rDNA and GSⅡsequences indicatded that six representatives of strains were classified into four groups on genus Bradyrhizobium、Rhizobium、Sinorhizobium and Mesorhizobium, and 16S rDNA sequencing homology was higher to GSⅡ sequencing homology. GSⅡ sequencing homology and 16S rDNA sequencing homology among six representatives of strains were respectively between 79.4%-89.8% and 87.5%-99.5%. Further, GSⅡ sequencing homology and 16S rDNA sequencing homology between the representatives of strains and phylogenetically closest reference stains were respectively from 88.9% to 99.6% and from 99.9% to 100%.