As one process of ecological environmental degradation, desertification caused land economic productivity and complexity decline or loss, not only affected the development of economic growth and social stability, but also hindered economic and social steady development. Soil moisture decides vegetation appearance and growth, even affects the entire ecosystem and affects the land productivity in the arid areas. It is the key factor to determine ecological function. However, no report can be found about the spatial and temporal variations of soil moisture in different vegetation zones in dune slacks on the mobile dunes. We selected 3 dune slacks in mobile dunes and 183 samples totally. The result showed that the soil moisture in different vegetation zones changed with seasonal fluctuation and decreased from spring to autumn. Soil moisture at 0-10cm. 10-20cm. 20-30cm soil layers was reduced the most in sand falling zone, herbosa zone and shrub zone was the second, sand removing zone was the least. Soil moisture in herbosa zone (0-10cm. 10-20cm. 20-30cm) was more than other 3 zones. The results indicated that herbosa is a better vegetation recovery pattern to conserve soil water in mobile dunes; the restoration of vegetation in the mobile dunes should be mainly by herbaceous vegetations.