To investigate the Ns genome donor of Leymus and to elucidate the origin of Xm genome of Leymus, Random Amplified Polymorphic DNA (RAPD) markers were used to analyze 13 Leymus accessions, together with 14 taxa from related Triticeae genera. A total of 156 clear and reproducible DNA fragments were amplified by 24 RAPD primers, among which 154 fragments (98.72%) were found to be polymorphic. The main results showed as following: (1) the Leymus species were clustered together first, and there is the closest phylogenetic relationship between L. akmolinensis and L. angustus; (2) Leymus species have Ns genome, which come from Psathyrostachys, and different Psathyrostachys species could serve as the donor for different Leymus species; (3) The partial Leymus species had a close phylogenetic relationship with Hordeum chilense, Australopyrum retrofractum, Lophyrum elongatum.