Gully erosion damages land resources and causes site-off environmental problems. But little gully erosion model included in soil erosion models. It is necessary to study soil moistures in a gully watershed for establishing a gully erosion model and restoring vegetation. A gully watershed was selected in Ansai County, Shaanxi Province to study soil moisture spatial distribution and its seasonal and annual variations. From 1998 to 2000, soil moistures were measured every April to October by using TDR systems installed in different gully positions. The analyzed results showed that there were obvious different soil moistures in a gully watershed. The higher water content was in the gully top which was 10.3% of volume. Soil water was poorer in gully sides and increased from upper slope to lower slope, which were 6.3%, 6.4% and 10.4% respectively. For gully cliff, soil moisture was close to wilting point, which was the driest soil in a gully watershed. Gully floor had relative higher soil moisture of 7.7%. During the rainfall season from April to October, soil moistures decreased in the whole gully system, but there were fluctuations corresponding to the occurrence of rainfall events. The higher the soil moistures were, the higher the seasonal variations were. Soil water content in the gully floor had the largest varied range of 10.3% during the rainfall season. But soil moistures in gully cliff had no any change during the season, even during 3 years. From 1998 to 2000, soil moistures of all the positions in the gully watershed reduced continually. Gully top and lower slope only had 8.1%~8.8% of soil water and other locations were near to wilting point. The spatial distributions and seasonal or annual variations of soil moistures in different potions of a gully watershed depends on rainfall supply largely. For the gully floor, soil water content was influenced by the runoff generation besides rainfall supply. It would be valuable to further study the relationship between rainfall types and runoff generation and soil moisture variations.