Aiming at the insulation failure caused by surface flashover phenomenon in high voltage equipment, this paper summarizes the key issues such as basic characteristic measurement means, influencing factors and occurrence mechanism of surface flashover phenomenon. In this paper, the main research progress of surface flashover observation methods and their influencing factors are introduced, and the specific mechanism of surface flashover process and the role of surface charge in the process of surface flashover are discussed. Among them, the external factors, the electrode - medium interface layer factor and the vacuum - medium surface layer factor affect the surface flashover as well as the surface charge accumulation and dissipation, and the specific mechanism is different. In the mainstream mechanism of surface flashover, the SEEA theory has a complete description of the initial process of surface flashover, while the ETPR theory has a better explanation of the development process of surface flashover. In addition, surface charge provides the necessary charge for the generation of flashover along the surface, and its accumulation and dissipation play a decisive role in the development of flashover along the surface. Developing insulating materials with low secondary electron emission coefficient and high surface conductance and surface modification technology will be the key research direction in this field in the future.