Currently, there is limited research on the groundwater regime in the southern low hilly areas, and there is still a lack of quantitative expression for the spatial non-stationarity relationship between groundwater levels and their influencing factors. Taking the typical hilly area of the Fuhe River Basin in Jiangxi Province as an example, this study analyzes the groundwater regime in the hilly area. Based on the geographically weighted regression model and multi-source data, it quantitatively expresses the contribution ranking of influencing factors to groundwater levels in the mountainous and plain areas, and compares the differences in the effects of influencing factors on different temporal and spatial scales. The results show that the groundwater regime in the study area is mainly influenced by precipitation and evapotranspiration, with large monthly fluctuations in groundwater levels and a decreasing trend from south to north in terms of spatial distribution. Both the mountainous area and the plain area are significantly influenced by precipitation and ground surface elevation factors, with the mountainous area having a larger contribution from the percentage of surface water area factor to groundwater levels, while the plain area is more influenced by the land surface temperature factor. The effects of influencing factors exhibit obvious spatial heterogeneity. With the increase in precipitation, the influence of precipitation factor on groundwater levels gradually increases. The ground surface elevation factor shows a positive effect in the mountainous area, while the land surface temperature factor generally exhibits a negative effect in the plain area.