Clarifying the impact of rainfall on soil moisture in the loess hilly area is great significance to accurately assess the impact of rainfall pattern changes on the structure and function of ecosystem. In this study, the artificial pure forest of Caragana korshinskii that had been abandoned for 23 years after being planted in the abandoned farmland in the loess hilly area of northern Shaanxi was taken as the research object. The soil moisture sensor was used to monitor the soil volume water content in different soil layers, and the responses of soil water supplement increment in different soil layers to rainfall characteristics (rainfall, rainfall duration and rainfall intensity) were discussed. The results showed that: (1) Soil water consumption and replenishment were mainly concentrated in the 0-500 cm soil depths, and the monthly variation in the vertical profile were "double peak" (April-May), "single peak" (June) and "double peak", and the change rate decreased with the increasing of soil depth. (2) When the rainfall was more than 4 mm, surface soil moisture could be effectively replenished. When it exceeded 142.8 mm, the replenishment depth could reach 200 cm soil layer. The soil moisture replenishment increment of the long-duration heavy rainfall was less than that of short duration heavy rainfall, however, the replenishment depth of long-duration heavy rainfall was deep and the peak time was long. (3) The influence of rainfall characteristics on soil moisture decreased with the increasing of soil depth. The influence of rainfall and rainfall duration was mainly in 0-50 cm soil layer, and the influence of rainfall intensity was in 0-30 cm soil layer. The logarithmic fitting of rainfall (rainfall duration) and soil water replenishment increment was the best. While the logarithmic fitting of rainfall intensity and soil water replenishment increment was the best, which could explain 39%~76% of soil water replenishment increment (rainfall), 0~97% (rain duration) and 1%~91% (rain intensity), respectively. To sum up, the greater the rainfall and the longer the rainfall duration, the greater the soil moisture replenishment increment. And the soil water consumption and rainfall replenishment was in 0-500 cm soil layer and 0-200 cm soil layer, respectively.