Low temperature is widely regarded as the most important limiting factor in the alpine meadow ecosystem. The alpine meadow ecosystem represents a huge carbon pool that is witnessing rapid increases in air temperature. While warming may alleviate the low-temperature limitation to primary production, warming may decrease soil moisture by increasing the evaporation level and may stimulate ecosystem respiration. In addition, N may become a limiting factor if primary production enhances. This study focuses on how warming affects the H₂O and N cycles, and how changes in these cycles affects carbon balance. First, the Biome-BGC model (V. 4.2) is parameterized and validated using real time data from the Haibei Alpine Meadow Ecosystem Research Station, Chinese Academy of Sciences and then this model is used to assess the effects of warming. In the model increasing air temperature was set at 1.2-1.7℃ based on the previous results of the free-air temperature enhancement (FATE) experiment at the station. The simulated results showed warming increases evapotranspiration and decreased soil moisture in the growing seasons, while slightly increasing soil moisture in non-growing season. Warming slightly but significantly increases the litter’s decomposition rate, and increases the annual concentration of inorganic N in soil by 7.9%. Warming promoteed both gross primary production (GPP) and heterotrophic respiration (R_H). The increases of SLAI (specific leaf area index) and assimilation rates leaded to increased GPP. The GPP increased by up to 34.3% every year. Because of the enhancement of microbial activity and increased litter input, the warming increased average annual R_H by 17.2%. R_H increased by 24.9% during the non-growing seasons, whereas it only increases by 12.3% due to decreasing water content in soils during the growing seasons. The GPP increase surpassed R_H during the growing seasons. Warming increased annual mean NEE (net absorption) by 29.6%. The results suggest that in the future warming scenario, the alpine meadow ecosystem may remain a weak carbon sink. Warming plays the most important role in the change of carbon flux. Carbon flux is also influenced by water loss caused by warming, and the role of water loss in some processes was prominent. The balance between the effects of warming on litter decomposition and on plant absorbing resulted in increase of soil inorganic N. N availability and H₂O are not limiting factors on plant growth in the short term, but this may change in the long-term; this should be studied further in the future. Comparisons with newly published simulation results related to the Tibetan Plateau are also discussed.