[Objectives] Land use change within the potential extent of desertification in China (hereafter referred to as the desertification area) is jointly regulated by climate, geomorphology, and hydrological processes, while its spatiotemporal heterogeneity remains insufficiently characterized under a unified regionalization framework. [Methods] Based on the delineation of potential desertification areas in China, this study established a three-dimensional regionalization framework integrating eco-hydrological regionalization, climatic aridity regionalization, and geomorphic-functional dimensions. Using land use data from 1990, 2000, and 2020, we analyze the structural characteristics and evolutionary patterns of land use across different regions, and further examine desertification-related dynamics from five key processes, including transitions between vegetation and typical desert land types, vegetation cover changes, forest-grass conversions, variations in water bodies and wetlands, and cropland expansion. [Results] Results showed that, over the past three decades, both typical desert land types and vegetation (forest and grassland) have generally declined, while forest and grassland vegetation did not increase correspondingly. Grassland area and cover declined overall, while cropland, built-up land, and water bodies continued to expand, revealing that a reduction in typical desert land types could not be simply equated with vegetation recovery. Land use change exhibits pronounced regional heterogeneity. In the Northwest Inland Zone (I), vegetation recovery is mainly observed in mountainous areas, whereas degradation dominates in plains. In the Qinghai-Tibet Plateau Zone (II), vegetation recovery is primarily concentrated in semi-humid zones. In the Yellow River-Hai River-Liao River Temperate Zone (III), the trend of cropland-to-forest conversion is significant and also concentrated in semi-humid areas. In the Northeast Cold Zone (IV), newly increased cropland mainly originates from grassland and water bodies, although its growth rate has slowed. [Conclusions] Overall, climatic aridity-humidity conditions determined the basic regional pattern of land use, while geomorphic functions further differentiated the pathways of vegetation recovery and degradation. These findings suggest that desertification control should avoid using the reduction of typical desert land types as the sole indicator of ecological recovery. Instead, regional management should account for the contrasting water-resource conditions between mountain runoff-generation zones and plain water-dissipation zones, with particular emphasis on grassland conservation and on coordinating land-use intensity with regional water-resource carrying capacity, thereby providing a basis for region-specific desertification management.