Abstract: This research aims to elucidate the spatiotemporal evolution trends of cropland conversion to forest or fruit production in the southern mountainous regions, with a specific focus on Fujian Province, China. A comprehensive approach was adopted over the study spanning five-time points from 2000 to 2020. A raster dataset comprised the land-use data, natural environmental variables, locational conditions, and economic policy factors. Subsequently, the cropland conversion to forest or fruit production was identified through spatial overlay analysis. The optimal parameter was utilized to geographically weight the detector model. The terrain gradient classification and spatial autocorrelation analysis horizontally and vertically determined the spatiotemporal features of cropland "conversion to forest or fruit production". Furthermore, the indicators were selected from three dimensions – natural environment, locational conditions, and economic policies – to detect the key factors and interactive influences on the significant cropland conversion to forest or fruit production. The research findings indicated the following key results: 1) Cropland conversion to forest or fruit production exhibited an overall trend of "steady development followed by a sudden increase." The fourth time period witnessed a significant surge, with the converted area reaching 98 670.24 hectares. The primary regions of conversion were gradually shifted from east to west, with an increasing number of counties with conversion rates exceeding 1%. There was a reduction in the large-area patches, as the number of patches increased. 2) Horizontally, the degree of conversion shared the transition from "higher in the east, lower in the west" to "higher in the west, lower in the east." Moran's I increased from 0.396 to 0.672, indicating a clear spatial clustering of the conversion behavior. 3) Vertically, the cropland conversion to forest or fruit production exhibited a distinct topographical gradient, primarily occurring at elevations between 0 and 1 000 m, slopes of 0°-2° and 10°-20°, and terrain position indices ranging from 0.1 to 0.8, particularly in regions with the shaded and semi-shaded slopes. 4) Multiple factors were dominated in the cropland conversion to forest or fruit production. At the single-factor impact level, the economic policy demonstrated a higher explanatory power, compared with the natural and locational factors. The impact of each factor varied in the different periods, but the elevation, distance to residential areas, and GDP consistently emerged as the dominant factors with substantial explanatory power. At the multi-factor interaction level, there was mutual reinforcement among factors, with the more pronounced interactions between different types of factors within the same category. Notably, the interaction between locational factors and other elements exhibited a particularly significant enhancement. The cropland conversion to forest or fruit production complicatedly evolved from the combined influences of natural endowment, locational conditions, and economic policies. The differentiated management should be adopted in the control measures for the cropland conversion, according to the baseline conditions of cropland and the diverse driving mechanisms involved. Additionally, the cropland occupation and replenishment can be balanced to promote the spatial displacement between plain areas with forest or fruit production and hilly cropland. The research findings can offer valuable scientific insights for the coordinated development of cropland production and diversified agriculture in the southern mountainous regions.