Ecological space undertakes the mission of maintaining regional ecological balance and provides sustainable ecological space services for society. It is a basic guarantee that regional land ecology can continuously provide society with the benefit of natural space services. In this study, the Poyang Lake Ecological Economic Zone, which is fragile in its natural ecological environment, was used as the research area. Based on relevant practical experience and research results of domestic and foreign scholars, spatial information technology based on RS and GIS was used to evaluate the importance of ecosystem services and the sensitivity of ecosystem; the corresponding evaluation indicators were selected, according to local conditions, to identify the critical ecological space of Poyang Lake Ecological Economic Zone. The results showed that the area of critical ecological space in Poyang Lake Ecological Zone was 27751.25 km², accounting for 52.55% of the total area of the study area; the urgent ecological space was 17125.31 km², accounting for 32.43% of the total area; the crisis ecological space was 4431.19 km², accounting for 8.39% of the total area; and the crucial ecological space was 6194.75 km², accounting for 11.73% of the total area. In land-use ecological-security conflict analysis, 14.29% of cultivated land and 9.31% of construction land are in a critical ecological zone.