Abstract: Abstract: Continuous improvement in both culture-dependent and-independent tools of microbial diversity analysis and extending of animal species into minor ruminant not only add tremendous information into the public database of rumen microbial diversity, but also reveal that the structure of rumen microflora is affected by host genotype, growth development and health conditions and demonstrate a dynamic character with ratio regime and season. In the functional point, fiber degradation, methanogenesis and biohydrogenation of unsaturated fatty acid and related microbial issues were highlighted from physiological, genomic or metagenomic point of view. Although much progress has been made in 2009, how certain keystone members of the microbiota operate to maintain the stability and functional adaptability of this microbial organ still need to be answered which necessitate the combination of high throughput methods and multivariable analysis．

Key words: Key words: rumen microbe; diversity; fiber degradation; methanogenesis; biohydrogenation