To investigate the responses of soil carbon， nitrogen， and phosphorus content and their stoichiometric characteristics in alpine wetlands of the Qinghai-Tibet Plateau to nitrogen and phosphorus addition， this study took the Gahai swamp meadow as the research subject. Through field manipulation experiments， four treatments were established： control （CK）， nitrogen addition （N）， phosphorus addition （P）， and combined nitrogen-phosphorus addition （NP）. The research explored the response patterns of soil nutrient contents and their stoichiometric characteristics in the 0~40 cm soil layer to three consecutive years of nitrogen and phosphorus addition. Results indicated that nitrogen， phosphorus， and combined nitrogen-phosphorus applications reduced soil pH， bulk density， soil water content， and ammonium nitrogen content while increasing aboveground biomass. Nitrogen application alone increased nitrate nitrogen content. All treatments reduced soil organic carbon and C∶N ratios while increasing total nitrogen and N∶P ratios. Individual nitrogen and phosphorus addition significantly increased total phosphorus content and decreased C∶P ratios， whereas the combined addition of nitrogen-phosphorus showed no significant changes in these parameters. Correlation analysis revealed highly significant negative correlations between C∶N and total nitrogen， as well as N∶P； significant positive correlations existed between C∶P and organic carbon， N∶P， and between N∶P and total nitrogen. Soil total nitrogen emerged as the primary driver of changes in soil stoichiometric characteristics. Effect analysis indicated positive effects of different nutrient additions on both total nitrogen and N∶P ratios. In summary， nitrogen and phosphorus additions exerted significant effects on soil carbon， nitrogen， and phosphorus， providing insights for predicting responses of alpine wetland ecosystems to climatic and environmental changes and formulating conservation strategies.

Nitrogen and phosphorus addition  /  Swamp meadow  /  Gahai wetland  /  Soil stoichiometric characteristics