Abstract: In order to reveal the temporal and spatial evolution laws of ecological flow research in China and provide solid scientific support for the sustainable utilization of water resources and the construction of ecological civilization. This study analyzed the research hotspots and development trends of ecological flow in China in recent 20 years and constructs a scientific research map. By retrieving ecological flow literature from CNKI databases and using CiteSpace to visualize author collaboration, institutional collaboration, keyword clustering, co-occurrence, and burst detection, the research hotspots and evolutionary trends were revealed. The research results showed that from 2004 to 2023, research on ecological flow in China had grown rapidly, with the number of publications peaking in 2022 (136 articles). A total of 331 core authors were identified, with two authors publishing more than eight articles. The collaboration network involved 206 institutions, with Xi′an University of Technology and the China Institute of Water Resources and Hydropower Research having the highest number of publications (≥30 articles). Keywords co-occurrence analysis indicated that ecological flow, ecological scheduling, and ecological water demand were the main research hotspots, forming 10 keyword clusters. Burst analysis revealed that reservoir scheduling, the Yangtze River Basin, the Yellow River Basin, and climate change had become key focus areas in recent years. Future research should strengthen collaboration among core authors and institutions, optimize watershed ecological protection and compensation mechanisms, and deepen multidisciplinary cooperation and policy-oriented studies.