With the advancement of global urbanization, ecosystem conservation and sustainable land development have become major issues. In this context, the uncoordinated and imbalanced development of the land-centered human-environment system requires urgent attention, especially in rust belt cities that pose critical challenges to regional land system sustainability. Therefore, taking Changchun City from 1990 to 2020 as an example, we identified and evaluated the ecosystem service (ES) balance and land use conflict from the perspectives of internal support and external development pressure. Based on the land system adaptation and conflict results, a coupling coordination degree model (CCDM) was constructed to investigate the spatio-temporal characteristics of land system development. The results indicated that there was an obvious downward trend in the regional ES balance, while areas with higher ES balance were mainly distributed in the eastern ecologically sound areas, and southern built-up areas presented deficient ES balance levels (i.e., demand exceeding supply), with a significant expansion trend from 1990 to 2020. Land use conflict was especially prominent in areas experiencing rapid rural-urban transformation, and the hot spots expanded noticeably. The spatio-temporal differences in the coupling coordination degree of ES balance and land use conflict were significant, whereas the land system of the study area has always been dominated by a balanced development pattern throughout the research period, except for the urban center, which tended to be in a stage of uncoordinated development, with the ES balance blocked. These findings suggest that it is necessary to coordinate urban and adjacent regions through regionally integrated efforts to alleviate the ES imbalance. This research can provide a scientific reference for analyzing regional land system states, coordinating the sustainable spatial development of ecosystems, and implementing revitalization strategies to achieve win-win land system goals.