Soil-atmosphere carbon dioxide (CO₂) exchange is a key carbon cycling process in terrestrial ecosystems. To assess the effects of atmospheric N deposition on the C budget of an alpine meadow ecosystem on the Qinghai-Tibetan Plateau, it is necessary to explore the responses of soil-atmosphere CO₂ exchange to N addition. Since 2007, a multi-form, low-level N addition experiment has been conducted at the Haibei Alpine Meadow Ecosystem Research Station on the Qinghai Tibetan Plateau. Three N fertilizers, NH₄Cl, (NH₄)₂SO₄, and KNO₃, were added at four rates: control (0 kg N hm^-2a^-1), low N (10 kg N hm^-2a^-1), medium N (20 kg N hm^-2a^-1), and high N (40 kg N hm^-2a^-1). Each N treatment has three replicates. Each plot has an area of 9 m² (3 m × 3 m) and a 2 m isolation band is set between adjacent plots. During the growing season (May to September), soil CO₂ effluxes were monitored weekly by static chamber and gas chromatograph techniques. Parallel to the flux measurements, soil temperature at the soil surface and at 5 cm and 10 cm depth and soil moisture at 10 cm depth were recorded. Soil ammonium and nitrate contents and aboveground biomass were measured monthly to examine the key factors driving soil CO₂ efflux. N addition did not alter soil temperature, but significantly changed soil moisture content. Both low and high levels of N addition tended to reduce soil moisture, whereas a medium level of N input maintained soil moisture. This mainly depended on the soil moisture balance of precipitation, soil evaporation and plant transpiration. N addition slightly increased the soil NH⁺₄-N pool but did not significantly change the NO^-₃-N pool. Competition for soil available N between plants and soil microorganisms, priority use of nitrate by plants, and removal by livestock grazing are responsible for this lack of significant accumulation in the soil nitrate pool. In control plots, soil CO₂ efflux from alpine meadow soils ranged from 120.9 to 1000.4 mg CO₂ m^-2 h^-1, with an average of 544.7±40.0 mg CO₂ m^-2 h^-1. N addition significantly increased aboveground biomass and soil CO₂ efflux. Ammonium-N fertilizer promoted soil CO₂ efflux more significantly than did nitrate-N fertilizer, which was mainly attributed to competition and cooperation in the use of multi-form nitrogen between plants and soil microorganisms. Soil CO₂ efflux was mainly driven by soil temperature, followed by aboveground biomass and the NH⁺₄-N pool. This indicates that the contribution of heterotrophic respiration to CO₂ efflux from the alpine meadow soil is greatest, followed by autotrophic respiration from plant roots. Soil NH⁺₄-N accumulation can increase the contribution of root autotrophic respiration and soil microbial heterotrophic respiration, suggesting that CO₂ emissions from alpine meadow soil are sensitive to exogenous N input. Chronic atmospheric N deposition will stimulate CO₂ emission from alpine meadow soils on the Qinghai-Tibetan Plateau in the short term. We can also deduce that chronic N deposition may accelerate degradation of the grazing alpine meadow ecosystem.