In order to study the relationship between elevation and populations of Populus szechuanica var. tibetica located on the Qinghai-Tibet Plateau, 24 pairs of SSR primers were used to study genetic diversity and structure of populations in Sejila Mountain of the southeastern plateau. A total of 126 alleles was detected from 469 individuals, with an average of 5.25 alleles per locus, a PPL (polymorphism percentage level) of 100%, and a relatively high expected heterozygosity (HE) for populations at high and low altitudes (0.48 and 0.49, respectively), Analysis of molecular variance (AMOVA) showed that the differentiation between populations was accounted for 6.38% to of the total anand the most variation existed was among the individuals within a population. That estimation of A differentiation coefficient (Fst) of Fst was 0.02 also supported the conclusion that the differentiation between populations was in low level. T and the value of gene flow (Nm) was 9.89 at which was in a very high level. also supported the conclusion that the differentiation between populations was at a low level. In conclusion, no geographical separation and differentiation of populations along the altitude of the genetic diversity and population structure of populations sampled from Sejila Mountain showed no evident pattern along altitude gradientwere observed. As a result, The strategic cconservation and utilization of Tibetan poplar could be facilitated on the base basis of understanding of differentiation and distribution patterns of the species. The and study about on mechanism of adoption of aptation to a high altitude could be processed smoothly.