Ecohydrology is a new and developing frontier science for nearly 20 years, which studies the interrelation between hydrology and ecology on the watershed scale, and seeks the new approach to ecological balance and sustainable utilization of water resources in watershed. Now the ecohydrology has been paid great attention in academic circles in China, but the research is just on its beginning stage. Internationally, although many studies have been carried out, especially in the United States, Europe and Canada, but there are still divergences for some basic problems, such as the definition of ecohydrology. Ecohydrology and some relevant concepts are reviewed and discussed briefly in this paper, including the definition of ecohydrology, ecosystem approach, habitat quality and its composition, environmental factors affecting biological integrity, analytical approaches, and concepts in river ecology. The purpose is to deepen the knowledge of ecohydrology.