Understanding the microbial linkages among the soils, plants and animals is crucial for maintaining the balance of an ecosystem in grazed grasslands. However, previous studies always focused on the biotopes of soil, phyllosphere and faeces separately and little has been known about the microbial distribution and migration among these biotopes. In this study, a systematic survey to investigate the overlap and differentiation among the various microbiotas of biotopes and how the environmental filter on microorganisms served for the ecosystem was conducted at the molecular level. Our findings revealed the biotopes' role of biofilter leads to the discrepancy of microbiota distribution among the soil, phyllosphere and faeces. The substantial overlaps between soil and phyllosphere in fungi, bacteria and archaea indicated that soil could potentially perform as the microbial reservoir for phyllosphere. However, there was only fungal mass migration running through the ecosystem to link all the biotopes while there are little communal OTUs of bacteria and archaea. These findings promoted our understanding of the biotope contribution to microbial migration and improved the knowledge of microbial linkages in the grazed grassland ecosystem.