Abstract: Metagenomics based on study of ecological community gene function is a brand-new discipline. It tries to use culture-independent approaches,and it offers enormous scope and potential for microbiology. It comprises isolation of DNA,library construction and screening of target gene clone,and can be used in the discovery of new gene and biocatalysts and in the study of microbial biodiversity in a community.The methodology of metagenomics and the application of metagenomics in rumen have been briefly summarized.

Key words: metagenomics; rumen microbiota; library constructing