To explore the improvement effect of desertification soil by adding of dewatering sludge from sewage treatment plant as soil amendment and determine the appropriate adding amount of sludge, the soil structure, nutrition index, water retention character were tested under the dewatering sludge doping content of 5%,10%,15%, 10%,25%,30%,25%.Three kinds of soil which were suitable for farming were chose as control test sample. The results showed that density of soil particles and soil bulk density reduced（r=-0.99, r=-0.89），while soil porosity increased when the addition of sludge to the sandy soil (r=0.79). When the sludge adding amount was more than 10%, the improvement effects of soil bulk density and porosity reduced. However, organic matter content, moisture content and water-holding capacity appeared linear growth with mixing amount of sludge (r>0.99). The water retention ability of improved sandy soil was better than contrast soil. Amounts of nitrogen and phosphorus were significantly positive linear correlated with the adding amount of sludge.（r>0.95）. The content of total nitrogen and phosphorus of improved soil were closed to the comparative soil when the sludge amount was 15%~25%, while the content of total potassium was almost no changed. However, the effective potassium content of sludge effectively increased. The best blending amount was 10%~25% the physical and chemical properties of ameliorative desertification soil was closed to contrasted soil and suitable to vegetation growth.