【Objective】The Tibetan Plateau has a unique function in physical environment and ecosystem because of its unique geographical features. Grazing is the main practice of management of grassland ecosystems and plays a crucial role in maintaining biodiversity and ecological processes. So volumes of researches have been reported on plant communities and soil physicochemical properties of the grasslands in the Tibetan Plateau, however, little has on the impacts of grazing on diversity of soil nematodes in this alpine regions, although soil nematodes play an important role in process of the ecosystem. The unique properties of the alpine grassland mean that grazing may have impacts distinct from what the other terrestrial ecosystems have on soil nematode communities. It is, therefore, critical to do more researches on impacts of grazing on population and biodiversity of the soil nematode communities in this region and how grazing affects soil nematode communities, through altering plant communities or soil physicochemical properties.【Method】In this study effects of grazing on soil nematode communities, plant communities and soil physicochemical properties, relative to degree of grazing (light, Moderate and heavy) were explored. Effects of timing of sampling and grazing management and their joint effects on these indices were analyzed via repeated measurements and ANOVA. Changes in biomass of the nematode communities and the plant communities and soil physicochemical properties were observed and the data gathered were analyzed to explore relative importance of alternative pathways of the effect of grassing on nematode communities with the structural equation modeling (SEM) method.【Result】The effects of grazing on nematode communities, plant communities and soil physicochemical properties were related to degree of grazing, time of sampling and their interactions. Population of bacterivores nematodes, biomass of plant roots, biomass of plant litter, soil moisture content and soil organic carbon content were all the highest in grasslands lightly grazed (p＜0.05); biomass of ruderal weeds was the highest grasslands moderately grazed; and population of omnivorous nematodes was the lowest in grasslands heavily grazed (p＜0.05). Soil nematode communities was significantly related to plant communities and soil physicochemical characteristics (p＜0.05). SEM analysis shows that grazing affects plant feeders and bacterivores nematodes by changing plant communities. 【Conclusion】This study reveals that grazing can change soil nematode communities, biomass of plant communities and soil physicochemical properties. All the findings in this study suggest that changes in nematode communities are mainly caused by changes in plant communities. This study is the first effort that has been done by the authors on effects of long-term grazing on soil fauna in alpine meadows of the Tibetan Plateau and its mechanism. This study may have laid down a foundation for future researches on ecological processes of above-ground and underground ecosystems. It is suggested that in future studies, emphasis should be laid on effects of plant community diversity and individual plant properties on soil nematode communities.