Abstract: In order to research and evaluate the difference of water conservation capacity between different types of forest vegetation, we used positioning research method and arranged measuring points, and examined the diversification of soil moisture content in the understory of 0--30 cm. The focus of our research is to probe into the evolutionary trends of soil moisture at Juglans mandshurica natural secondary forest and Larix gmelinii plantation in the rainy season at the mountain ous region of eastern Liaoning. The results showed that: there are differences in soil moisture content and water storage capacity between J. mandshurica natural secondary forest and L. gmelinii plantation. It is mainly expressed as follows: from the top to the bottom of slope, the distribution of the research area is first J. mandshurica natural secondary forest and then L. gmelinii plantation and that can be divided into three functional areas: J. mandshurica forest, landscape boundary region and L. gmelinii forest. The soil moisture in each soil depth of landscape boundary region is significantly higher than that in J. mandshurica forest and L. gmelinii forest. Along the contour the trend of soil moisture shows first a steady status and then fluctuation. In the vertical direction, the trend of soil moisture in three functional areas shows a decrease with soil depth, which can be classified into three layers: rapid change, gradient change and stable layers. By using Moving Split-window Analysis, we defined the influence range of soil moisture at different soil depths at J. mandshurica natural secondary forest and L. gmelinii plantation during the rainy season(August to October). The results were that, the influence range of soil moisture in soil layer 0--10 cm is the width of 25 m with the type of gradual boundary; the influence range of soil moisture in soil layer 10--20 cm is the width of 20 m with the type of gradual boundary; the influence range of soil moisture in soil layer 20--30 cm is the width of 10 m with the type of gradual boundary in August and October and abrupt boundary in September. This research can provide a scientific basis for forestation design and rational management and renovation of forest water conversation capacity.