Abstract: Through sampling in Poyang Lake wetland soil，this paper researched the adsorption experiment and used infrared spectroscopy characterization，and studied the adsorption characteristic of ammonia nitrogen on soil humins． Results showed that the humin accorded with the Freundlich model，and the adsorption was multiple． The aromatic ring，fat，phenols or groups，such as Si—O keys，were likely to be involved in the adsorption reaction and NH + 4 －N was likely to be through hydrogen bonding，proton transfer or Van der Waals force to be adsorped on humin． pH，temperature and the amount of humin had certain influence on the adsorption reaction．