Gannan region, an important ecological barrier in the Gan Jiang River basin, is a typical southern mountain-hill area in Jiangxi Province, China, and its ecological protection is of great significance. In this study, using data of 5-year intervals from 1990 to 2015, the land-use change dynamics and ecosystem service value in the Gannan region was investigated through the application of remote sensing, geographic information technology, and spatial statistical methods. In addition, the driving factors of spatial and temporal differences in ecosystem service value for the Gannan region and the spatial correlation between three factors-per capita GDP, population density and urbanization rate, and ecosystem service value-were also investigated. The results showed that (1) the dynamic degree of land use in the Gannan region increased over the 25 years of investigation from 0.06 to 0.13; (2) the ecosystem services assessment showed that the total value of the ecosystem services in the Gannan region declined by 20.42×10⁸ yuan over the study period. The ecosystem services provided by the forest ecosystem led to the highest loss in value. High forest cover and scattered arable land are the main reasons for the high regulation service value and the low supply service value in the Gannan region; (3) the per capita GDP and the population density and urbanization rate were the main driving forces that led to decrease regional total ecosystem service value. They were also highly consistent with the local spatial correlation for ecosystem service value. The higher urbanization rate led to the lower ecosystem service value, and had local low-high and high-high aggregation distributions. This study provides a theoretical basis and a decision support mechanism for the rational layout and protection of ecological land in this southern hilly region. The results could lead to improved ecological barrier functions.