With continual developments in medicine and health care, parts such as microminiaturization, stability of transferring fluid, and flow pulsation and backflow for piezoelectric pumps, especially valve-less piezoelectric pumps, have increased their requirements in recent years. Volume piezoelectric pumps cannot generate continuous output and pressure due to their inherent period and fluctuation, nor can they avoid the phenomena of backflow, pulsation and choking of the micro valve block. Meanwhile, rotation piezoelectric pumps cannot meet the requirements of security transport and stabilization in vivo due to their own complexity and uncontrollability. As a result, the exploration of novel operating principles of piezoelectric pumps becomes particularly important. Based on the phenomenon of driving fluid with single-flow by swing, this paper summarizes the research on three kinds of caudal-fin-type swing type valve-less piezoelectric pumps, which are developed in the fluid driving unit of the State Key Laboratory of Mechanics and Control of Mechanical Structures in Nanjing University of Aeronautics and Astronautics.