Abstract: A pot incubation experiment was conducted to compare the effects of three structure modifiers (polyacrylamide, β-cyclodextrin, and humic acid), used widely at home and abroad, on formation of waterstable aggregates and supply capacity of nutrients in a silty coastal soil. The result showed that application of each of three structure modifiers could improve the formation of water-stable aggregates in the soil, and the amounts of >0.25 mm water-stable aggregates in the soil increased with increasing the rates of the modifiers. The improved effects decreased in the order of polyacrylamide > β-cyclodextrin > humic acid. The optimal dosage of polyacrylamide and β-cyclodextrin for modifying soil structure was about 0.20%. Application of humic acid had no significant effect on supply capacity of nutrients in the soil. However, application of polyacrylamide and β-cyclodextrin could change supply capacity of nutrients in the soil. The soil, added with modifiers after application of chemical fertilizers, had weaker supply capacity of nutrients as compared with control without application of any amendments. While the soil, added with chemical fertilizers after application of modifiers, had stronger supply capacity of nutrients as compared with control.