Abstract: Two-phase flow in channels and water and gas management of proton exchange membrane fuel cell （including H2/O2 PEMFC and direct methanol fuel cell） have a great influence on its performance and life. Visualization technique is one of the most powerful tools to study the two-phase flow in a fuel cell. The formation and development of gas bubbles or water droplets in channels are truly presented by the visualization study. Moreover, it can help us to understand the evolution mechanism，optimize water and gas management and improve the performance of the fuel cell. This article reviews the experimental and theoretical studies relating to visualization of two-phase flow and transport in proton exchange membrane fuel cells，discusses the wettability of the diffusion layer and water transport mechanism, presents a variety of techniques for visualization and puts forward some disadvantages and the development direction of visualization study.