Abstract: Electrochemical and photochemical liquid-environment transmission electron microscopy (TEM) has been applied in the field of energy catalysis in recent years because of its direct observation of solid-liquid interface dynamically and at real time. First, the platform design of introducing electrical and light signals into transmission electron microscopy in liquid environment was summarized. Second, the applications of this technology in several typical energy catalytic systems, such as electrocatalytic hydrogen generation, carbon dioxide reduction and photocatalytic hydrogen production, were introduced and summarized. Finally, the limitations of this technology were analyzed and the solutions were put forward. Based on this, the future development direction of this technology was prospected. Electrochemical and photochemical liquid-environment transmission electron microscopy technology not only provides powerful technical support for studying the mechanism of various catalytic reactions, but also offers the opportunities to solve the resolution problem, and the illusion caused by the interaction between electron beam and material should be paid attention to by researchers.