To investigate the effects and mechanisms of plant species diversity on grazing behavior of livestock in grassland, a Tibetan sheep rotational grazing experiment was conducted in an alpine meadow of the Tibetan Plateau. The study mainly included plant species diversity, feeding speed, foraging speed and feeding time of Tibetan sheep, and then calculated the average daily feed intake of Tibetan sheep. The results showed that species richness was significantly and positively correlated with the feeding speed of Tibetan sheep (P<0.05); foraging rate, foraging time and the average daily feed intake were sensitive to stocking rate (P<0.05), which increased in summer and autumn but decreased in winter and spring. Shannon Wiener index had a significantly negative correlation with the feeding time of Tibetan sheep (P<0.05). There was a significantly positive correlation between Shannon Wiener index and daily feed intake of Tibetan sheep in warm season or 8 sheep/hm² (P<0.05). Pilelou index was significantly negatively correlated with the feeding speed time of Tibetan sheep (P<0.05); and Pilelou index was significantly negatively correlated with the daily feed intake of Tibetan sheep in warm season or 8 sheep/hm² (P<0.05). Species richness contributed more to the grazing behavior of Tibetan sheep, and stocking rate and time of grazing Tibetan sheep were more sensitive to species diversity. Hence, species diversity was a good predictor of grazing behavior of Tibetan sheep. Grazing management influenced the grazing behavior of Tibetan sheep by affecting the plant species diversity. Grazing behavior is not only a key indicator for evaluating the nutritional value and livestock productivity of grasslands, but also a basis for grassland health management. Therefore, clarifying the interactions between species diversity and grazing behavior of Tibetan sheep can help to better improve the productivity of Tibetan sheep and maintain ecological health of grassland.