Abstract: There are a large number of microorganisms in the rumen of ruminants, which are the key factors affecting the health and production performance of ruminants.With the development of metagenomics technology, new ways and methods have been opened up for the study of rumen microorganisms. Macrogenomics technology can be used to study the diversity of rumen microorganisms, the effect of rumen microorganisms on host physiological metabolism, and the interaction between rumen microorganisms and host, and it also has the ability to excavate functional genes related to metabolism. This paper reviewed the development background of metagenomics technology, as well as its main applications and shortcomings in the study of rumen microorganisms in ruminants, including the effects of host and its living environment on rumen microorganisms, the effects of concentrate-to-coarse ratio in diet and feed additives on rumen microorganisms, antibiotic resistance genes（ARGs） in rumen microorganisms, and the effects of rumen microorganisms on milk production performance of ruminants. At the same time, the application prospect of metagenomics technology in the study of rumen microorganisms was also prospected, in order to provide reference for the study of rumen microorganisms in ruminants.