Aims Characteristics of a strain Pediococcus pentosaceus Q6 isolated from Elymus nutans growing on the Tibetan plateau and its effects on E. nutans silage fermentation stored at low temperature were investigated. Methods and Results Sugar fermentation pattern and growth profiles of the strain Q6 and its reference strain APP were characterized. The strain Q6 and APP were inoculated to E. nutans at ensiling respectively; and ensiled at different temperatures (10, 15 and 25 degrees C) for 30, 60 and 90 days. The results indicated that Q6 could grow at pH 3 center dot 0 and at 4 degrees C. In contrast to APP, Q6 could ferment mannitol, saccharose, sorbitol and rhamnose. Lower pH in Q6-treated silages fermented for 60 days at 10 and 15 degrees C was found compared with the control and APP-treated groups. For the silages that were stored at 10 or 15 degrees C, the greatest lactic acid content were detected in Q6-inoculated silages ensiled for 30 and 60 days respectively. There were no differences in pH and lactic acid content between Q6- and APP-treated silages ensiled at 10 and 15 degrees C for 90 days respectively. Conclusions Inoculation of the strain P. pentosaceus Q6 could improve fermentation quality of ensiled E. nutans at the early stage of ensiling stored at low temperature (10 or 15 degrees C). Significance and Impact of the Study The selection of P. pentosaceus inoculants for improving silage quality at low temperature, which provides a candidate strain to make high-quality silage in regions with frigid climate.