A new species of Leymus Hochst. (Poaceae, Triticeae) from Inner Mongolia, China, L. pubens H. X. Xiao, is described, illustrated, and compared with its closest relatives. This species was initially identified as L. chinensis (Trin.) Tzvelev, but the upper surfaces of its leaf blades are spinulose, and the internode below the spike, upper half of the rachis, rachilla, and lemmas are sparsely puberulent. A key is provided for L. pubens and closely related species of Leymus. The identification of the new species is also supported by nuclear ribosomal ITS and chloroplast trnL-F sequence analyses.