The carbon and nitrogen composition and stable isotope abundance of plants collected from the alpine meadows and seeded pasture at the headwater region of the Yellow River were analyzed with mass spectrometer Isoprime100.The purpose was to determine the type of plant photosynthesis and response of carbon and nitrogen stable isotopes abundance to vegetation succession.The results show that:(1)plant carbon content of 58 species varies between 28.64% and 51.55% and nitrogen content is from 0.89% to 4.04%.The δ¹³C abundance varies between -29.50‰ and -24.69‰ and the δ¹⁵N value is from -4.57‰ to 8.32‰.(2) The plant carbon content of different sites is in the order of mix-seeded pasture (45.54%)>non-degraded meadow (43.18%)>light degraded meadow (42.18%)>heavily degraded meadow (39.68%).The plant nitrogen content of different sites is in the order of non-degraded meadow (2.30%)> mix-seeded pasture (2.28%)>light degraded meadow (2.13%)> heavily degraded meadow (2.10%).(3) The δ¹³C values of plants in mix-seeded pasture,non-degraded meadow,light degraded meadow and heavily degraded meadow are -25.63‰,-26.57‰,-26.76‰ and -27.91‰,respectively,and the δ¹⁵N values are -0.63‰，0.32‰，2.76‰ and 0.26‰,respectively.Alpine degradation can result in decreased plant carbon and nitrogen content.All species analyzed are C₃ plants and no C₄ and Crassulacean acid metabolism (CAM) plants were found.The low annual mean temperature may be the main factor restraining the distribution of C₄ plants.The δ¹³C values decrease with degradation,but the δ¹⁵N values have no such tread.