Abstract: Chromosomes of two octoploids C.S Thinopyrum bessarabicum (AABBDDJJ, 2n=8x=56) and GHK Thinopyrum elongatum (AABBDDEE, 2n=8x=56) were Cbanded and karyotypes were analyzed with metaphase chromosomes, respectively.The results showed that terminal Cbanding were observed in both chromosomes of Th.bessarabicum and Th. elongatum, but the Jgenome of Th.bessarabicum had prominent terminal Cbands, which not present in that of Th.elongatum except chromosome E 1.On the other hand, the chromosomes of Th.elongatum showed several interstitial Cbands, while Th.bessarabicum did not.The chromosome pairing in octoploid hybrid between C.S Th.bessarabicum and GHK Th.elongatum was analyzed and octoploid hybrid showed a mean pairing of 15.50Ⅰ+5.03 Ⅱ + 14.20Ⅱ+0.40Ⅲ+0.21Ⅴ with 2.5 bivalents paired by chromosomes of Th.bessarabicum and Th. elongatum.Based on Cbanding patterns, most chromosomes of Th.bessarabicum and Th. elongatum showed univalents.Therefore, it can be concluded that they have no very close relationship and should have different genomes.