In order to explore the crux of the traditional industrial agglomeration city, this paper starts from the perspective of solving the predicament of sustainable development,taking Mid-southern Liaoning industrial base as an example, a comprehensive evaluation index system is established to assess its sustainable development level from 2007 to 2021, and the weighted summation technique of indicators based on the entropy weighting method of coefficient of variation is adopted to introduce the coupled coordination degree model and the obstacle degree model, and the theory of complex adaptive system (CAS) is embedded in the analytical process, combining quantitative and qualitative research to comprehensively assess the sustainable development of Mid-southern Liaoning industrial base. The study shows that: (1) The level of sustainable development of Mid-southern Liaoning industrial base has a significant stage, and now it is in the stage of rebound of economic development, but the level of sustainability is still weak. (2) Economic development is a shortcoming that constrains sustainable development in the region, and environmental quality is a dominant sustainable type. This phenomenon provides an entry point for understanding the phenomenon of "negative decoupling" or "weak decoupling". (3) The level of sustainable development and coupled coordination degree has serious spatial polarization and significant regional imbalance, showing a high-low-high evolution characteristic from north to south, with spatial heterogeneity; the level of coupled coordination degree has a tendency to be coordinated to a better level, and is in the transition stage from barely coordinated to primary coordinated. (4) Economic strength is the main factor limiting economic development; infrastructure development has a greater impact on people's livelihood and well-being systems; realizing a dynamic balance between resource scarcity and inefficient use of resources is the focus of efforts to promote sustainable development of resources; and overexploitation of natural green spaces has increased pressure on the ecological quality of the region. (5) In the face of the complex and interactive challenges in the process of urban development, it is necessary to organically combine the adaptive management of the government, the adaptive change of enterprises and the adaptability of local residents, and to promote the mutual reinforcement of science and technology and policy adjustments, so as to realize the virtuous circle of sustainable development. This paper regards the urban sustainable development system as a typical socio-ecological complex adaptive system, and analyzes the mechanism of the coupled evolution of sustainable development in such traditional industrial agglomerations as Mid-southern Liaoning, which provides a new way of thinking about the adaptive governance of sustainable development in urban agglomerations.