Late embryogenesis-abundant (LEA) protein is one of the components involved in desiccation tolerance (DT) by maintaining cellular structures in the dry state. In this study, a member of the group 3 LEA, MwLEA1, was cloned from Mongolian wheatgrass (Agropyron mongolium Keng) based on a homologous sequence from wheat (Triticum aestivum L.). Its full-length cDNA sequence was 705 bp, encoding a protein of 187 amino acids. The amino acid sequence comparison revealed its high homology with LEA proteins from other plant species. The deduced MwLEA1 protein had five repeat 11-amino-acid motifs, with a molecular weight of 19.4 kDa and a theoretical isoelectric point of 8.8. Subcellular localization indicated that the MwLEA1 was localized in the nucleus of the onion epithelial cell. Under water stress conditions, MwLEA1 exhibited different expression levels, which was higher in root and shoot but lowest in leaf. The expression profiling under different stresses indicated that MwLEA1 played roles in responses to water, salt stresses as well as abscisic acid (ABA) regulation. The gene of MwLEA1 was transformed into tobaccos by Agrobacterium tumefaciens-mediated method. Eleven regenerated plants were analyzed by polymerase chain reaction (PCR) and southern blotting, and 6 of them were proved to be transgenic plants.