Abstract: The karyotype analysis of exotic plant Solidago Canadensis L. in Bangbu,Anhui province was reported . The results are as follows :the number of chromosomes is 2n = 50 , morphological variations is not obvious to the 25 pairs of chromosomes, with all of them are median and submedian centromeric chromosomes , relative length ratio between the longest chromosome and the shortest one is 1.72, there is no SAT in 50 chromosomes, the karyotype formula is 2n = 50 = 38m +12sm + 6Bs,the karyotype type is 2A. 6 B-chromosomes in somatic cells of Solidago Canadensis L. were firstly reported in this study, the number of B-chromosomes is the same in different cells, the relation between B-chromosome and invisibility of Solidago Canadensis L.in the new habitat was discussed too.