Abstract: Sandy soil is not conducive to the survival of vegetation as the poor water-holding capacity and coarse texture of sandy soil. The water-holding capacity of sandy soil would be improved if its grain size distribution could be adjusted reasonably,being suitable for the vegetation reconstruction. In order to find appropriate improving materials and mixing ratio to improve the water-holding capacity of sandy soil,the experiment is conducted to mix 0～50 μm bentonite and 150～200 μm sand particles. The bulk density,soil water content,total porosity,capillary porosity,non-capillary porosity and cumulative evaporation of the mixed soil are measured,and the effect of the addition of Bentonite on the water-holding capacity of sandy soil is analyzed. The results show that the addition of Bentonite significantly reduces the soil bulk density and non-capillary porosity,and increased the total porosity and capillary porosity of the soil,and improves the water holding capacity of the soil. With the increase in the proportion of Bentonite,the bulk density and non-capillary porosity of soil decrease gradually,and the total porosity and capillary porosity increase gradually. Compared with the control group,the addition of Bentonite increases the soil saturated water capacity and residual water,decreases the cumulative evaporation,significantly prolongs the evaporation time,and enhances the water retention capacity of the soil,which is more conducive to plants. With the increase in the proportion of Bentonite,the soil saturated water holding capacity and residual water shows a trend of increasing gradually,while the cumulative evaporation shows a trend of decreasing gradually. The addition of Bentonite can also make the loose aeolian sand grains on the soil surface stick together,make the soil surface become dense and hard,and restrain the evaporation of soil moisture to a certain extent,this slows the release of water from the soil,allowing the soil to retain more water over a longer period of time. The results can provide technical support for the ecological restoration of sandy soil in the arid area of northwest China.