With the gradual development of the restoration and protection of the water ecosystem, the research and safegard of ecological flow have received much attention. However, there is a lack of systematization of the literature in the field of “ecological flow” and a lack of in-depth understanding of the main and topical contents of the research in this field. In order to gain an in-depth understanding of the progress and current status of research on ecological flows, this paper searched Web of Science core databases for scientific papers published from 1999 to 2021 on the topic of “ecological flow”. The retrieved 18,128 research papers on ecological flows were also visualized and analyzed by using CiteSpace software for documents per year, category, country and institution distribution, co-citation, and clustering. The results show that research papers on ecological flows have shown an increasing trend since 1999. The categories of disciplines involved cover a wide range of disciplines such as environmental science and ecology, water resources, and so on. The United States ranks first in the number of publications and has a high influence. A total of five clusters were obtained through keywords clustering, with more overlapping areas, hydrological modeling, and aquatic ecosystems are the mainstream of research in the field of ecological flow. “Ecological flow” is still in a phase of rapid development, with the depth of research gradually increasing and the breadth of research expanding. In a long time, the keywords “r package”, “ecological flow”, “loess plateau”, “yellow river” and “emission” will be the center of the field of “ecological flow”.