<p>Amid the ongoing urban–rural transformation, conflicts among production, living, and ecological spaces are increasingly evident, making these spaces’ coordinated development a central strategy for achieving regional sustainability worldwide. Nevertheless, few studies have examined the spatial characteristics of production-living-ecological functions (PLEF) through a network lens. This study uses Qianshan, Anhui Province, a typical mountain-plain transition zone, as a case study. It develops a PLEF evaluation framework based on land use data and integrates the gravity model and social network analysis (SNA) for comprehensive analysis. The results indicate that production function (PF) and living function (LF) networks exhibit similar spatial patterns, showing a core-periphery structure centered on the southeastern plain, where favorable topography, concentrated infrastructure, and sustained policy support have reinforced functional agglomeration. In contrast, the ecological function (EF) network shows a polycentric and resilient pattern in the western mountainous areas. Functional connectivity is influenced not only by physical distance but also by infrastructure and industrial ties. PF and LF networks rely on transport and industrial links but face structural vulnerability from core dependency, whereas EF networks leverage ecological corridors for resilience. These findings provide insights for promoting urban–rural integration, optimizing spatial patterns, and advancing sustainability in mountain-plain transition zones.</p>