Abstract: Xanthopappus subacaulisis an endemic medicinal plant growing in the alpine meadow of the Qinghai-Tibet Plateau（QTP）.To explore the influence of Quaternary climatic oscillations on the population genetic structure and distribution pattern of X.subacaulis,3 chloroplast DNA fragments（psb A-trn H,rbc L and psb I-psb K）from 123 individuals of 20 populations were sequenced and analyzed respectively in the present study.The results showed that 6 haplotypes were detected in X.subacaulis,among which H1 was an ancient haplotype.All populations of X.subacaulis had haplotype H1 except for P7.H3,H5 and H6 were private haplotypes,among which H3 was a private haplotype of population P7,and H5 and H6 only existed in P18.H2and H4 were mainly distributed in the population of Qinghai Lake basin.The total genetic diversity（H_e）and nucleotide diversity（π）were 3.101 and 0.008 903,respectively.The genetic variation among populations（68.98%）was higher than that within populations（31.02%）,and the genetic differentiation among populations was relatively higher(F_ST=0.689 85,P＜0.01).The genetic differentiation coefficient N_STof populations（0.727）was higher than that of G_ST（0.656）（P＞0.05）,which indicated that there was no obvious phylogeographical structure in the sampling regions.The results of mismatch distributions and neutrality tests revealed that the population of X.subacaulis might have experienced recent expansion.Therefore,the study suggests there are micro-sanctuaries in Qinghai Lake basin of Qinghai Province and Lintan region of Gansu Province during the Quaternary glaciations,and suggests that the Quaternary climate change and QTP uplift shape the modern geographical distribution pattern of X.subacaulis.