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As the largest and highest grassland unit on the Eurasion continent, the Qinghai-Tibetan Plateau (QTP) plays a critical climatic role governing the Asian monsoon and is an important animal husbandry zone. Yaks are one of the two major ruminant species, playing an increasingly important role in supplying milk and meat to local residents and maintaining the ecological environment on the QTP rangeland. The piosphere effect, defined as a radial pattern of grazing animal influence on grassland is common in herbivore grazing systems where, for example, animals are penned overnight. However, to date, no direct quantification of animal distribution exists, which hinders the progress of studies on the interactions between grazing animal and vegetation. In this study, we selected a typical household-level ranching grassland with alpine meadow on QTP and monitored: 1) the hourly spatial distribution of each yak; 2) the monthly vegetation dynamics on fixed locations using unmanned aerial vehicle (UAV). We found 1) grazing pressure decreased with increasing distance from night pens in the early growing season; however this pattern reversed in the late growing season; 2) vegetation biomass increased with increasing distance from night pens through whole growing season; and 3) no relation was found between grazing pressure/vegetation dynamics with river distance in the pasture. The monitor and analysis method realized dynamic monitoring of whole animal herd with high frequency, resolution and efficiency, and low cost. Widespread and long-term monitoring will improve our understanding of piosphere and be beneficial for grassland grazing management.