Abstract: This paper deals with the comparison of C-banding patterns of all Rattus species (8 species) in China.And there are some differences among their C-banded karyotypes.The evolution of C-banding patterns of 8 species of rats has been studied,and the following factors maybe facilitate karyotypic variability:loss of centromeric heterochromatin,interstitial heterochromatin,terminal heterochromatin and heterochromatic arms.Based on the different characteristics of C-banded karyotypes,R.yunnanensis,R.shkkimmensis and R.turkestanicus may be classified into three independent species.Moreover,a cluster dendrogram has been presented in this paper by the fuzzy aggregation.It shows that these 8 species are able to divide into two groups:R.rattus sladeni R.sikkimensis for the first group and R.flavipectus,R.yunnanensis,R.nitidus,R.losea,R.turkestanicus and R.norvegicus for the second.