In this paper, the shrub windbreak and sand-fixing sand barrier of Bairin Youqi in Chifeng in the east of Horqin Sandy Land is the research object, three different types of plant barriers including hedysarum laeve grid sand barrier, Salix gordejevii and hedysarum laeve grid sand barrier and caragana and hedysarum laeve patch sand barrier are respectively selected, and the shifting sandy land is selected as a contrast at the same time to study its influence on the soil moisture of sandy land in the method of field locating observation method from early May to late September of 2005. Except for the contrasted sandy land, the monthly average soil moisture in each layer of plant sand barrier presents a fluctuation trend. The monthly change trend of soil moisture in the 10~20cm soil layer of hedysarum laeve grid sand barrier is the same as that of caragana and hedysarum laeve patch sand barrier. The soil moisture in 20~40cm soil layer of the three plant barriers in every month shows a big change, with the fluctuation range larger than the contrasted sandy land. The 20~60 cm soil layer is the area where the roots of sand barrier plant are centralized, therefore, the soil moisture in the root intensive area is reduced. The monthly change trend of soil moisture in 60~80cm soil layer of hedysarum laeve grid sand barrier, caragana and hedysarum laeve patch sand barrier is the same as that of the contrasted sandy land. The monthly change trend of soil moisture in the 80~100 soil layers is basically same. The minimum value of monthly average soil moisture of all kinds of plant sand barriers appears when the contrasted sandy land is 1.40%, and the maximum value appears when caragana and hedysarum laeve patch sand barrier is 4.79%, 3.4 times higher than the contrasted sandy land. The annual dynamic condition of soil moisture can be divided into: consumption period from April to June, supply period from July to August, stable period in September, which shows that the plant sand barrier is favorable for increasing the soil moisture.