A study was carried out to explore composition and characters of humus in coastal paddy soil.Results show that the surface soil layer was the highest in organic carbon and N content regardless of humus fractions.In tightly bonded humus relatively stable in structure and humus acids,C/N ratio fluctuated less,while in loosely bonded humus and fulvic acids,it did in a wider range.The formers showed an accumulating trend in soils with the age of paddy planting,and the highest degree of aromatization and the most complicated structure in 1000-year old paddy soil.