Abstract: The characteristics of seasonal dynamics of alkaline hydrolysis N in marsh soils of `closed' wetlands and `open' wetlands were studied. The results show that the changing tendency of alkaline hydrolysis N concentrations in surface soils shows a shape of anomalous `N' in the two typical sites, as for other soil layers, the contents of alkaline hydrolysis N change gently, but increase for each soil layer in autumn. The changing processes of alkaline hydrolysis N contents in soils from each soil layer can be fitted by three order polynomial, and these models give a good fit.