The fast growth of China's economy and society has brought severe consequences on the country's environ-mental quality and natural resources. In order to overcome these obstacles, the Chinese government proposed the concept of high-quality development in 2017, aiming to promote the comprehensive, sustainable and balanced development of society, economy, resources and the environment. Exploring the interactions within the Social -Economic-Resource-Environment (SERE) system in urban agglomeration regions can help policy-makers achieve high-quality sustainable urban development. On account of the concept of high-quality development and the theory of complex systems, we constructed the SERE system. Taking the Jingjinji (JJJ) urban agglomeration from 2011 to 2019 as a research sample, we first evaluated the comprehensive quality of the SERE subsystems at two scale levels using the entropy method. Then, the level of coordinated development among the subsystems was studied by building a coupling coordination degree (CCD)model. Finally, the effect of the four subsystems on the CCD was analyzed by using a panel regression model. The results of the study found that first, the SERE system's comprehensive development quality at the scale of the whole JJJ urban agglomeration showed an upward trend from 2011 to 2019. The resource subsystem always contributed the most, the economic and social subsystem contributed moderately, and the environmental subsystem contributed the least. Secondly, the comprehensive quality of all cities' SERE subsystems showed different degrees of growth, with notable spatial differences. The comprehensive quality levels of social, economic and resource subsystems in Beijing and Tianjin were signifi-cantly higher than those in Hebei. Thirdly, the SERE system's CCD in each city showed various growth ten-dencies. The proportion of severely unbalanced cities decreased from 84.62% to 61.54% during the study period, and regional development became more coordinated. However, there were still obvious spatial differences; Beijing and Tianjin consistently performed better, and the scores of cities in Hebei province were generally low. Fourthly, the degree of coupling coordination among the subsystems was positively correlated with their comprehensive quality. The elasticity of the environmental subsystem was the largest, which was essential to the coordinated development of the SERE system. These findings can offer governments valuable references for adopting appropriate policy measures which promote high-quality, sustainable and coordinated urban development.
