Abstract: The coordinated development of rural population, land, and industry is critical for rural revitalization and sustainable development in less-developed regions. Taking the Qinling-Daba Mountains as a case study, this paper develops a county-level evaluation system for the population-land-industry (PLI) nexus and applies the coupling coordination degree (CCD) model and the Geodetector method to examine its development level, spatiotemporal evolution, and driving factors from 2010 to 2020. The results show that the overall development level of the three subsystems remained relatively low during the study period, although static coupling strengthened continuously. The share of areas with high coupling levels increased from 36.91% to 47.10%, with these areas concentrated mainly along the southern foothills of the Daba Mountains and in the Nanyang Basin. By contrast, dynamic coupling was dominated by negative development patterns, with the negative development type involving all three subsystems accounting for 42.23% of the study area. Coupling coordination remained predominantly at the primary coordination level, accounting for approximately 30% of the study area, with pronounced spatial heterogeneity, indicating that synergies among the three subsystems remained limited. Socioeconomic development, human activities, and the natural environment were the principal drivers of spatial differentiation. Overall, coordination among rural population, land, and industry in the Qinling-Daba Mountains improved to some extent, but stronger coupling did not translate into a comparable improvement in coordination. These findings highlight the need to integrate population development, land use, and industrial spatial planning and to adopt differentiated territorial spatial governance strategies, providing insights for promoting rural sustainability in less developed regions.