Abstract: In order to find out the effects of super absorbent polymers(SAP) on physical and chemic characteristics of soil and apply it reasonably on drought resistance and water saving,soil moisture constants,soil density,pH values,soil expansion ratios and soil hardness of SAP-mixed soil were measured at experimental station,Agricultural University of Hebei.The three kinds of SAP were offered by Lvbao Company,Xining,Qinghai Province.Results indicate that SAP can make soil moisture constants and soil porosity increased markedly,but soil bulk density of SAP-mixed soil decreased.Soil expansion ratios increased by 65%-170%.SAP had little effects on the soil pH.The hardness of SAP-mixed soil obviously decreased,and the hardness of control soil was 5.2-32.9 times as much as that of SAP-mixed soil.