The ecological environment is the basis of high-quality economic development, and the coordinated development of the two is of great significance for promoting regional sustainable development. This study takes 31 cities in the middle reaches of the Yangtze River as samples, constructs an evaluation index system of the ecological environment (EE) and high-quality economic development (HQED), and uses a comprehensive evaluation method and a coupling coordination degree model to determine the development level, coupling coordination relationship, interaction coordination relationship and space–time evolution characteristics of the two. The results show that: (1) In the sample period, the overall level of EE and HQED increased simultaneously, but the two indexes of each city showed obvious heterogeneity. (2) EE and HQED have a coupling coordination relationship; the coupling degree (CD) is in a high coupling stage, and the coupling coordination degree (CCD) is in a good and moderate coordination state. (3) In the interactive coordination relationship, the CCD sequence of subsystems is coordinated development > shared development > innovative development > open development, and pressure subsystem > response subsystem > status subsystem. This study provides a new evaluation perspective for EE and HQED and puts forward suggestions for their coupling and coordinated development.

The harmonious development of human settlement environments (HSEs) and resident demands (RD) contributes to the sustainable development of areas. However, few studies have focused on development-level evaluations and analyses of coupling coordination between the two. This study used a comprehensive evaluation index model and a coupling coordination degree model to measure the development level, coupling coordination degrees, and spatial characteristics of HSE and RD in 31 regions of China. The results display the following: (1) The developing degree of HSE and RD continued to improve, with spatial heterogeneity, whereas the development level of RD and the regional economy was positively correlated; (2) the degree of coupling between the two was relatively high, with high-level coupling areas accounting for 77%, and the coupling coordination level included a medium level and primary levels; (3) in the coupling and coordination relationship between subsystems, living needs > security requirements > respected needs > social needs > self-realization needs, and environmental safety > ecological environment. This study offered a new research perspective for the sustainable development of areas and put forward suggestions for promoting development.

The ecological environment (EE) is an important factor affecting the sustainable development of the marine economy (ME): achieving coordinated development between the ME and EE remains a problem to be explored. From three perspectives—comprehensive development level, coupling coordination degree spatiotemporal analysis, and obstacle degree recognition—this paper explores the development level and spatiotemporal evolution characteristics of ME and EE coupling coordination in 11 coastal areas in China from 1999 to 2019. The results indicate the following: (1) During the research period, the comprehensive development levels of the ME and EE in China’s coastal areas continued to improve, with relatively high levels of economic structure subsystems and pressure subsystems. (2) There was a clear coupling relationship between the ME and EE, with a high degree of coupling, mainly consisting of high-quality coupling and good coupling. The increase in coupling coordination was significant, especially in Guangdong, Shandong, and Liaoning. (3) The analysis of the obstacle degree found that the crucial obstacle elements affecting the coordinated development of the ME and EE included the ME vitality subsystem and the EE response subsystem. Finally, policy suggestions are put forward, including promoting the development of an ecotype ME, promoting marine technology innovation, and adopting differentiated EE governance policies according to local conditions. This study helps evaluate the development capacity of the ME in China’s coastal areas and provides a basis for formulating targeted ME development strategies.