Elymus nutans Griseb. is a typical plant species of an alpine meadow. It has long played an important role in grassland animal husbandry and ecological management in Qinghai-Tibetan plateau. This study takes 20 wild Elymus nutans germplasm resources collected from Qinghai and Tibet as the research object. The hay yield, crude protein (CP), ether extract (EE), crude ash (Ash), acid detergent fiber (ADF), and neutral detersive fiber (NDF) were measured at the heading, early flowering, and milk maturity stages, respectively. The results showed that the hay yields of different E. nutans were significantly different (P<0.05), and the overall trend was to increase first and then decrease. The variation ranges of CP, EE, Ash, ADF, and NDF content of 20 E. nutans were 2.50%~11.73%, 3.63%~5.98%, 2.67%~6.79%, 31.78%~47.40%, 53.71%~72.08%, respectively. Analysing the yield and nutritional quality indicators of 20 E. nutans combined with the grey correlation theory method, it is concluded that GL5 has the best comprehensive performance at the heading and milk maturity stage, and HN4 has the best comprehensive performance at the early flowering stage. The top 5 in the three periods are GL5, HN4, GL6, HB1, and XZ2. These accession resources can be used as high-quality breeding materials.