Abstract: AFLP was used to analyze genetic diversity and differentiation of four populations of Flaveria bidentis(L.)Kuntze in Heibei province,chian; Information about four populations was also investigated. The results showing relatively high genetic diversity and significant genetic differentiations among four populations of F.bidentis(L.)Kuntze. The results of analysis indicating genetic diversity increased rapidiy accompanied by time and expanding of the population scale;the population in similar latitude of its origin had the highest genetic diversity.the formation of Genetic structure at present it is because its characteristics of life history and invasion ecology, and the stage of population. Seedsof F. bidentis are spread by w ind and water resulting in close biogeographic relationships among the populations occurring in neighboring regions