Soil moisture is a hydrological characteristic that plays a crucial role in the soil-plant-atmosphere continuum. The spatial distribution of soil moisture and factors that influence this distribution are extremely important to many ecological processes, especially in temperate mountain forest regions such as those in northern China. Nonetheless, little is known about soil moisture heterogeneity in typical subalpine forest lands or the controlling factors of soil moisture change. In this study, soil moisture content (SMC) was measured for depths of 0 to 60 cm in a typical watershed forest, dominated by Larix principis-rupprechtii, in Taiyue Mountain, Shanxi Province. We used Geographic Information System (GIS) data and geostatistical methods to examine the spatial heterogeneity of SMC and the factors (i.e., vegetation and topography) that influence it. SMC and its coefficient of variation (CV) decreased with increasing soil layer depth, exhibiting high to moderate variation under an assumption of time stability. At this small watershed scale, the best-fit model for SMC of the three layers (0-20 cm, 20-40 cm, and 40-60 cm) is the spherical model; the spatial autocorrelation distance ranged from 1.1 to 1.4 km. The distribution of SMC has strong spatial autocorrelation in all three layers. The degree of spatial heterogeneity of soil moisture in the 0-20 cm and 20-40 cm soil layers was higher than that in 40-60 cm layer. The structural characteristics of the middle layer accounted for the largest proportion of the total variation. Spatial variability of soil moisture was mainly (81.4% to 91.3%) controlled by natural structure factors such as topography, parent material, vegetation properties, and soil properties, while the influences of random factors such as sampling error, human disturbance, plant root distribution, and absorption were relatively small (8.7% to 18.6%). Moran's I values indicated that soil moisture had moderately aggregated distributions (0.44-0.51) across soil depths. The overall trend of SMC spatial distribution gradually transitioned from high to low values from west to east along with the waterline, an obvious gradient change. We also found that the spatial heterogeneity of soil moisture was mainly controlled by terrain factors in this mountainous catchment with homogeneous vegetation cover. Spatial variability of soil moisture was significantly correlated with topographic factors (such as aspect, slope, and elevation) and soil chemical properties (such as soil organic carbon and total nitrogen) (P < 0.01). However, it was weakly and negatively correlated with the normalized difference vegetation index (NDVI). Overlay analysis suggested that SMC was relatively high in regions where the three attributes of shady slope, smooth slope (<15 degrees), and high altitude overlapped. Moreover, soil moisture variation nearly matched the color depth change in a superimposed terrain map. Taken together, the results of this study provide data for planning the use of soil water resources in artificial vegetation restoration and construction of temperate subalpine forests and a theoretical basis for devising water management strategies.