How to prevent the equipment from malfunctioning and refusing caused by moisture in the switchgear has important practical significance. On this basis, the occurrence mechanisms of moisture and dewing in the switchgear and its key technologies for prevention and control are discussed. Firstly, the structural characteristics of the switchgear and the status quo of the prevention and control of the moisture and dewing are introduced. The mechanism, causes, conditions and hazards of the dewing of the switchgear are analyzed in detail. Then, the anti-dewing related measures and improvement methods are briefly described. These methods can effectively eliminate the failures occurred in the switchgear during operation. Lastly, an investigation scheme for the mechanism of moisture and dewing in switchgear is proposed. The scheme covers the analysis of the influence factors on the phenomena of moisture and dewing in the switchgear and the construction scheme of the simulation environment for the moisture and dewing mechanism research, and moreover, in which the concept of source is adopted to design a dry gas source based dehumidification system. Based on this scheme, the mechanism of moisture and dewing and the key technologies of prevention and control for the switchgear are prospected. This work is supported by Science and Technology Projects of China Southern Power Grid (No. GDKJXM20162530 (031800KK52160015)).