Abstract: Effects of temperature on dynamics of QinghaiTibet plateau Elymus nutans fermentation quality in the process of ensiling was investigated. The material was derived from Guoluo Tibetan Autonomous Prefecture of Qinghai Province. Plastic bag silage was finished in local area and was put in 15 ℃and 25 ℃ in the laboratory. The bags of each treatment were opened 2, 4, 6, 8, 12, 14, 30 and 60 d after ensilage. The results showed that pH value decreased slowly to 5.68, the lactic acid content increased to 1.44% at 15 ℃, and the fermentation quality was ineffective. 25 ℃ lowered the pH value and increased lactic acid content significantly (P0.05). The pH value was reduced to 4.27 and the lactic acid content was increased to 6.21%, which achieved good effects of silage. AN/TN value gradually increased with storage time, the acetic acid content increased significantly during the first 4 d (P0.05). Water soluble carbohydrate content decreased at the end of the fermentation significantly (P0.05) and remained stable. Temperature had no significant effect on the contents of crude protein, neutral detergent fiber and acid detergent fiber (P0.05).