The mechanisms underlying the retention of inorganic N were still not well understood in an alpine meadow on the Tibetan Plateau as well as in other high-altitude meadow sites greatly grazed and disturbed. We conducted field soil and dominant species foliar nitrogen natural abundance of stable isotope ratios (δ¹⁵N) under four grazing intensities. It was demonstrated that soil δ¹⁵N decreased significantly from 5.83±0.20‰ to 2.17±0.48‰ at 0-10 cm with the elevation of grazing intensity. Grazing reduced the degree of ecosystem N openness. The δ¹⁵N value of surface soil was mainly affected by soil total nitrogen. Furthermore, the degree of nitrogen limitation increased with grazing elevation for sedge family and Gramineae family plants.