Abstract: As a new technology, stable isotope analysis has developed rapidly in the field of ecology in recent decades. However, this technology has not been used widely in studies on alpine meadows. The abundance of stable isotopes and the densities of carbon and nitrogen in soils (0-30 cm) of different alpine meadows at the headwater region of the Yellow River were measured with Isoprime100. The soil δ¹³C ranged from -25.42‰ to -24.20‰. The soil δ¹⁵N ranged from 3.37‰ to 4.69‰, which is significantly higher than that in the atmosphere. The abundance of both δ¹³C and δ¹⁵N in soil increased with soil depth. The soil δ¹³C abundance was significantly lower in mix-seeded pasture soil than in soils of heavily and lightly degraded meadows (P<0.05), while the abundance of δ¹⁵N was significantly higher in mix-seeded pasture soil than in soils of heavily and lightly degraded meadows (P<0.05). The soil C∶N ratio ranged from 7.89 to 9.97. There was a significant (P<0.01) positive correlation between soil organic carbon content and total nitrogen content, and the relationship could be expressed by the following regression equation: TN(%)=0.0963×SOC (%)+0.0336 (R²=0.9619). The soil organic carbon density in the 0-30 cm soil layer in the lightly degraded meadow, severely degraded meadow, and mix-seeded pasture was 7.14, 6.67, and 6.46 kg/m², respectively, and the total nitrogen density was 0.83, 0.77, and 0.75 kg/m², respectively. Plant absorption and growth facilitated the outputs of ¹²C and ¹⁴N, leaving the heavier ¹³C and ¹⁵N isotopes in the soil. Vigorous growth and higher above ground biomass in the mix-seeded pasture consumed more soil ¹⁴N, resulting in higher concentrations of δ¹⁵N in the soil. Alpine meadow degradation and establishment of mix-seeded pastures may significantly reduce the soil carbon and nitrogen density, and this change will be mainly restricted to the 0-20 cm soil layer.