Abstract: Oat is an important grain and forage crop, which is grown in alpine region, where large temperature difference between day and night. Common lactic acid bacteria fermentation is not easy to success, because it needs the silage inoculants with strong temperature adaptability. In order to solve this issue, the main object was to research and select suitable lactic bacteria community for the rapid reduction of pH value of oat silage and for sharp increase of the flavors substrates like lactic acid and others at different temperatures, and to research its application effect on oat silage, such as oat silage quality and microbial diversity. This study took the natural microorganism of oat silage as the source of bacteria group, through a long-term restrictive culture and directional domestication on them, then screened two groups of lactic acid bacteria community at the temperature of 10 and 25 ℃, and named as LDS and MDS, respectively. The LDS and MDS tended to stabilization respectively during the screening process in the 10th generation. According to results of the qPCR-DGGE, the strains of LDS were mainly Lactobacillus, and the main strains of MDS was Pediococcus, Leuconostoc and Lactobacillus. LDS and MDS were added in the oat, the additive-free treatment was designed as control, and the silage was fermented under 10 and 25 ℃, respectively. The amount of lactic acid bacteria of 10 LDS was about 7400 times of its number of 10 CK, and the lactic acid content increased by 14.3% compared with 10 CK. The amount of lactic acid bacteria of 25 MDS was 27 000 times of its amount of 25 CK, and its lactic acid content increased by 30.3% compared with the 25 CK group. On the 10th generation of the fermentation of inoculated community, the microbial flora in silage was basically stable, and the inoculated strains were stably colonized in silage. LDS, MDS were inoculated oats at different temperatures (10 and 25 ℃), the lactate content of 10 LDS was 17.1% more than that of 10 MDS after fermentation for 30 days, acetic acid content was 23% more; The lactate content of 25 MDS was 19% more than that of 25 LDS, acetic acid content was 19.5% lower. The WSC（water soluble carbohydrate)，CP ( crude protein)，DMR (dry matter recovery) of treatment with LDS community were significantly improved, and the LDS could save the nutrients in oat better and improve its nutritional quality in the conditions of 10 and 25 ℃. MDS could be completely colonized at 25 ℃, but could not be colonized at 10 ℃; LDS could be colonized for two strains of bacteria at 10 and 25 ℃, so the LDS was more adaptable to temperature. This study provided a theoretical basis for the selection and application of lactic acid bacteria in oat silage in cold and alpine areas.