The rational use of rainwater resources can not only reduce the source of soil erosion, but also provide effective water supply to the local area. The Loess Plateau has less precipitation, large evaporation, and very scarce surface water resources. Therefore, the use of rainwater resources has become an important means for the Loess Plateau to deal with soil erosion, drought and water shortage. The core issue of rainwater resource utilization is to scientifically evaluate the local rainwater resource potential and its spatial and temporal distribution. For this reason, the distributed hydrological simulation technology was introduced to construct a distributed rainwater harvesting potential assessment model. It was dedicated to solving the core problems of rainwater resource utilization and evaluate the potential of local rainwater resources. The following conclusions were drawn by studying the typical Helong Region of the Loess Plateau. Under the dual influences of climate change and human activities, the surface runoff, soil water increment and the rainwater harvesting potential in Helong Region showed an upward trend after 1980s. The rainwater resources of most sub-basins in the Helong Region had a growing trend, and the rainwater resources could basically meet the water consumption under the current vegetation coverage. Climate change had a positive impact on rainwater resources with the contribution rate of 63.4% and the land use/cover change had a negative impact with the contribution rate of -36.6%. Therefore, the human activities imposed great effect on rainwater utilization pattern, and to fully develop the rainfallrunoff regulation technologies and improve the rainwater using efficiency were the key countermeasures to realize the ecology-economy synergetic development in the Loess Plateau.