Flow-electrode capacitive deionization (FCDI) is a special type of CDI, flowable slurry is used as the flow electrode instead of the fixed electrode. Compared to fixed-electrode CDI, FCDI has the advantage of unlimited desalination capacity, continuous desalination, and easy scale upgrade. Thus, FCDI has attracted the interest of many scholars. In this review, we summarize and compare the progress of FCDI researches in terms of the perspective of the design of FCDI cell structure, operating mode of FCDI, the component of flow phase and environmental applications. Finally, some possible problems of the current stage of FCDI technology are presented and the future direction of FCDI is outlined.