Moss layers comprise an important synusia under the Picea crassifolia forest, as they can change the soil moisture content by intercepting precipitation and reducing soil water evaporation. In this study, a shady slope at an elevation of 2700 m in the Pailugou Small Watershed of the Qilian Mountains was chosen as the study region to analyze the influence of moss layers on soil moisture content through observations performed from years 2010 to 2012 in the Picea crassifolia forest. The results showed that moss layers can dramatically reduce the spatial variability of soil moisture content during the growing season of the Picea crassifolia forest. The spatial variability of the soil moisture content was 62.2 mm in the sites without moss layers, and the coefficient of variation (CV) in spatial change was 17.3%. The CV in the sites with moss layers was 2.3%. The sites with moss layers only account for 1/7.5 of the without moss layer covered. So the spatial variability of soil moisture content showed significant differences between sites. The CV of the sites with moss layers was significantly lower than that of sites without moss layers (sig.< 0.05). The presence of moss layers could reduce the spatial variability no matter the level of rainfall. For example, the CV of soil moisture content was 19.8% in the rainless sites without moss layers, while the sites with moss layers showed only 1/3 of this variation under rainless conditions. The CV of soil moisture content was 15.2% in the sites with light rain and without moss layers, while the sites with moss layers only showed 1/3 of this variation under light rain conditions. The CV of soil moisture content was 15.4% in the sites experiencing continuous rain that did not have moss layers, while the sites with moss layers only accounted for 1/3.3 of the sites with continuous rain. Under rainless conditions, spatial differences in sites with moss layers were significantly smaller than those in sites without moss layers in soil layers at a depth of 0-15 cm. Under conditions of light or continuous rain, spatial differences between sites with moss layers had no correlation with the sites without moss layers in the 0-15 cm soil layers, as the function of moss layers in reducing spatial differences in soil water content was mainly reflected in the 15-80 cm soil layers.