The rational matching of urban land and population has become an important prerequisite for sustainable urban development. In this paper, the traditional urban land scale elasticity model was improved, and combined with the gravity model, the spatial interaction between land expansion and population change in 618 cities in China during the period 2006–2021 was investigated. The geographical detector method was used to reveal what drives them. The main results were as follows: (1) China’s urban land expansion rate was 1.83 times faster than the population growth rate during 2006–2021. After the implementation of the New-type Urbanisation Plan in 2014, the ratio of land expansion rate to population growth rate dropped from 2.46 to 1.12. (2) Among the six interaction types identified, land rapid expansion is the most significant, accounting for 41.59% of urban samples. (3) The geographical detector method found that the indicators of urban development rights such as the level of administrative hierarchy and the ratio of fiscal revenue to fiscal expenditure were the main factors affecting land expansion and that economic indicators such as gross domestic product and employment opportunities dominated population change. Fortunately, the intervention role of urban development rights has declined, and the constraints of market mechanisms, resources and environment have gradually become the dominant factors in urban land expansion and population change. These findings provide a theoretical basis for alleviating the human–land contradiction and achieving sustainable urban development.

Optimizing Ecological security patterns (ESPs) is critical for advancing territorial spatial restoration and fostering sustainable regional development. While research on ESPs’ construction has grown significantly, key challenges persist, particularly in the accurate identification of priority conservation areas and the integration of socioeconomic development with ecological conservation. To address these challenges, this study selects Jiangsu Province as a representative case. We move beyond single-factor assessments by combining ecosystem service importance evaluation with a multi-factor ecological sensitivity analysis (including water pollution, soil erosion, air pollution, and anthropogenic pressure). A comprehensive ecological resistance surface is then developed, incorporating both natural and anthropogenic disturbance factors, to evaluate spatial patterns of ecological security. Utilizing the Minimum Cumulative Resistance (MCR) model, we delineate ecological corridors and ultimately construct the ESPs by synthesizing ecological sources and corridors. Key results include: Jiangsu’s ESPs comprises 33 ecological patches (total area: 14,622.46 km², 13.71% of the study region), predominantly composed of water bodies, wetlands, and cultivated land. Thirteen ecological corridors (total length: 1920.38 km) primarily traverse cultivated land, construction land, and water bodies. The optimized ESPs strategy termed “Two Cores, Two Barriers, Three Belts, Multiple Corridors” offers a concrete spatial blueprint. The findings provide effective scientific reference for assessing and managing regional ecological security trends.