[Objective] This study aimed to investigate the changing patterns of soluble nitrogen（N） fractions in alpine wetland meadow soils in the context of long-term global nitrogen deposition. [Methods] Taking the Gahai wetland meadow soil at the northeastern edge of the Qinghai-Xizangan Plateau as the research object, the characteristics of soil soluble N fractions in response to N addition were investigated, relying on the experimental platforms that had been treated with N addition for three years [CK（no added N）, N1（4.14 g NH₄ NO₃） and N2（6.12 g NH₄ NO₃）]. [Results] 1) Compared to CK, the N1 treatment significantly increased the mass fraction of soil nitrate-nitrogen（NO₃^--N）（ 15.76%）, while the N2 treatment significantly increased the mass fraction of soil ammonium-nitrogen（NH₄⁺-N）（19.19%）（p＜0.05）. 2) Under different N addition treatments, soil soluble organic nitrogen（SON） density was the highest（106.14 kg/hm²）, followed by NO₃^--N density（92.41 kg/hm²）, and NH₄⁺-N density was the lowest（91.18 kg/hm²）. 3) The changes in the proportion of NO₃^--N, NH₄⁺-N and SON densities to total nitrogen（TN） were more significant under the N1 treatment than that under the N2 treatment, indicating a better enhancement of soil N supply potential of the N1 treatment. 4) PCA analysis showed that N addition had an important effect on the characteristics of soil soluble N components in the alpine wetland meadow of Gahai. Soil soluble N fractions under the N1 treatment were mainly regulated by TN, while under the N2 treatment, they were mainly regulated by soil organic carbon and microbial biomass carbon. [Conclusion] Low N treatment can increase the soluble N fractions of alpine wetland meadow and promote soil N transformation, while high N addition can have the opposite effect.