Exploring the sloping farmland use transformation in typically ecologically fragile areas and its impact on regional socio-economic and eco-environment is of great significance to make rational use of sloping farmland resources in mountainous areas and realize the sustainable development of socio-economic and eco-environment system. Based on the land use data of Fengjie County in 2000, 2010 and 2020, the methods of measurement of the transformation of sloping farmland use morphology, and evaluation of the level of socio-economic development and eco-environment quality are adopted. This paper reveals the general law of sloping farmland use transformation in the mountainous areas, comprehensively and quantitatively explores the impact of sloping farmland use transformation on regional socio-economic and eco-environment, and measures the driving mechanism of its coupling change types. The results show that:(1) from 2000 to 2020, the area of sloping farmland in Fengjie County reduced as a whole, mainly in the morphology of corridors and marginal patches, and the reduced sloping farmland was mainly converted to forest land with ecological function and orchard with ecological and economic function; (2) The level of socio-economic development and the quality of eco-environment showed an overall growth trend, and there existed significantly regional differences. The former showed a distribution pattern of high in the Yangtze River Valley-low in the mountainous area, and the latter showed a spatial pattern of low in the Yangtze River Valley-high in the mountainous area; (3) The coupling response types of sloping farmland use transformation to socio-economic development and eco-environmental quality can be summarized into five types:socio-economic and eco-environmental synchronous development type, socio-economic development and ecological retarded type, socio-economic retarded and ecological restoration type, low socio-economic development level type and low eco-environmental quality type; (4) Various types of socio-economic and eco-environment changes are mainly driven by factors such as sloping farmland use intensity, land use diversity and distance from the county administrative center. On the whole, the influence of socio-economic factors is greater than that of natural factors.