Abstract: In this paper, the population genetic structure of Erigeron breviscapus in three population of Yunnan was studied by the karyotype analysis and allozyme analysis. Lijiang , Karyotype analysis indicated that all the three populations are diplontic(2n=2x=18).The karyotype formula of Lijiang population is :2n=2x=18=6m+10sm(2SAT)+2st. Ten alloz-yme analyses show that the genetic variation exists within the populations. The genetic identities in the three populations are very high (I=0.9172), and the genetic distances are verysmall (D=0.0876). The genetic distances are positively related to the spatial distances.

Key words: Erigeron breviscapus