Based on a modified Leenheer fractionation scheme,dissolved organic matter (DOM) extracted from Huang-nitu under different land use were fractioned according to their polarities and charge characteristics by using XAD-8 resin.The characteristics were studied with the aid of elemental analysis,¹H-NMR and CP/ MAS-¹³C-NMR spectroscopy.It was preliminarily found that of the total DOM extracted from the paddy soils,HIM predominated,accounting for about 35%,HON accounted for 7%~15% and HOB for a little.As is shown by the elemental analysis,¹H-NMR and ¹³C-NMR spectra,HON was characterized mainly by longchain alkylate with 77.13% of aliphatic C.N from the DOM could be found primarily in fraction HON.Comparison between the spectra of HOA and fulvic acids (FA) indicated that both contained a large amount of carboxylic groups and that the former contained more carbohydrates and less aromaticity.Finally,fraction AIM consisted of high-branched polyphenols and humic bound carbohydrates,and fraction HIM contained a high amount of carbohydrates.