Abstract:The ITS regions of 2 closely related species Allium tuberosum Rotuer. ex Spreng. and Alllium ramosum L. in Allium Sect. Rhiziridium G. Don were amplified, cloned and sequenced. The genetic re-lationships among 10 materials of diploid, triploid, tetraploid and aneuploid in Allium tuberosum and All-lium ranwsum were reconstructed based on ITS1 + ITS2 sequences. The results demonstrated that the aver-age Kimura pairwise distance between Allium tuberosum and Allium ramosum was 0.0146. They are a pair of closely related species. Although it was gone through evolution by artificial selection and natural selec-tion, Allium tuberosum kept little differentiation from Allium ramosum. Sequences of ITS region show that there are no evident differentiation among the various diploid, triploid, tetraploid and aneuploid of Allium tuberosum.