Recent years have witnessed the rapid development of microfluidic technology and microfluidic devices as a multi-disciplinary research field. Compared to conventional methods, microfluidic technology enables us to precisely manipulate the small volume of multiphase fluids for chemical analysis, advanced materials synthesis, protein crystalliza-tion, single-cell cultivation and detection, information processing, etc. In this paper, we review the multiphase flow phenomena in microfluidic devices, summarize the fluid mechan-ics involved, describe various methods to achieve multiphase microfluidic flow, and analyze the state-of-the-art of applications and challenges in this field. Finally, numerical simulation methods and experimental measurement techniques for multiphase microflows are provided. Opportunities for future research and application of microfluidic devices are suggested.