The spatio-temporal variation is a ubiquitous feature of natural ecosystems, especially in semi-arid regions of Horqin. The purpose of this study is to characterize variations in moisture content in the 0–160 cm soil layers in situ by means of intensive sampling in both space and time. The results indicated that soil moisture content in the 0–160 cm soil layers exhibited a high degree of spatial and temporal variability. The degree of variability was dependent on the water content. The CV of mean water content in the 0–160 cm soil layers spanned from 18% to 177%, indicating a level of middle or high variability. The result also suggested that CV was dependent more on soil moisture level than on soil depth. A large increase in CV for the soil layers was observed in dry condition. The spatial and temporal variations of the water content were related to vegetation types and soil moisture. At a fairly definite range, the heterogeneity of water content caused by spatial autocorrelation was evidently higher in wet season (July-August) than in dry season (September-October). The distance of spatial autocorrelation was different in different seasons and depths. It was more consecutive for spatial trend in wet season than in dry season. Clearly, the consumption of water by shrubs increases the spatio-temporal variability of soil water.