【Objective】This study was oriented to characterize the evolution of organic nitrogen composition and bioavailabilities of its components with degradation of alpine wetlands, in an attempt to provide certain basic data for restoration of degraded alpine marsh wetlands. 【Method】Soil samples were collected from 4 types of wetlands, including relatively pristine marsh (RPM), lightly degraded marsh (LDM), moderately degraded marsh (MDM), and heavily degraded marsh (HDM) in the Zoige Wetland Nature Reserve. Organic nitrogen in the soil samples were fractionated using the Bremner method. Multivariate stepwise regression analysis was performed to determine contribution of each fraction of organic nitrogen to availability of soil nitrogen.【Result】With RPM turning into MDM and HDM, soil total nitrogen (TN) decreased significantly or by 33.4%~77.8% and 69.4%~93.7%, respectively, and alkalytic nitrogen (AN) by 36.8%~80.2% and 57.6%~82.2%, respectively, in content. In terms of contents of acidolytic ammonia nitrogen, amino acid nitrogen and unknown nitrogen, the four types of wetlands exhibited an order of RPM > LDM > MDM > HDM. With a marsh degrading, amino sugar nitrogen therein increased first and then decreased in content, and the proportion of amino sugar nitrogen and ammonia nitrogen to TN increased, while that of amino acid nitrogen to TN decreased. The main organic nitrogen fraction affecting the content of soil available nitrogen in RPM and HDM was ammonia nitrogen and unknown nitrogen, respectively; whereas that in LDM and MDM was amino acid nitrogen. 【Conclusion】 Degradation of the Zoige Alpine Wetland reduced the contents of soil TN and the fraction of acidolytic nitrogen, weakened nitrogen "sink" function of the soil, and changed the contribution of each organic nitrogen fraction to nitrogen availability.