Abstract: The degree of spatial heterogeneity of soil moisture and the ability of environm ental attributes to predict that heterogeneity were studied at 81 locations in D anangou catchment (3.5km²) in the semi arid Loess area of China. Soil moistu re measurements were performed biweekly at five depths in soil profile (0～5,10～1 5,20～25, 40～45 and 70～75cm) from May to September 1999 using time domain refl ectometry (TDRabstract It was observed that the mean and the spatial heterogeneity of soil moisture exhibit significant profile patterns. As the increasing of soil de pth, the mean soil moisture content increases significantly beginning at 0～5cm and the spatial heterogeneity also exhibits an increasing trend but beginning at 10～15cm. The temporal changes in the mean and the heterogeneity are also obvio us. During the measured periods, the mean moisture increases after precipitation events and is followed by a decline as the soil dries down, whilst the heteroge neity exhibits an opposite pattern. The spatial heterogeneity of both the time averaged soil moisture and the layer averaged soil moisture are influenced by t he environmental attributes at site scale (slope angle), hillslope scale (hillsl op e position and relative elevation) and watershed scale (precipitation and land u seabstract However, the relative roles of environmental attributes vary with soil dept hs and with seasonal evolution.