Abstract: Roof insulators of high-speed trains are important components to ensure the safe operation of trains. They play the roles of mechanical support and electrical insulation. Flashover of any insulator will lead to power supply interruption or even shutdown of high-speed trains. The Sichuan-Tibet railway faces the most challenges in the history of our country railway engineering due to bad and complex environments and more tunnel groups along the railway, thus, the high-speed train roof insulator faces the characteristics of plateau low pressure, high temperature and high humidity, and other extreme environments and climates, and the design and configuration of the insulator are different from those of transmission line insulator. Therefore, in view of fastening the train running under special circumstances, this article summarizes the present situation of research on the insulator flashover characteristics under different conditions by scholars at home and abroad, including high altitude low pressure, high speed air flow, temperature, and humid and large temperature difference environments; moreover, according to the actual train operation condition, the problems existing in the research of insulator flashover features are reviewed. At the same time, based on the complex environment of Sichuan-Tibet railway, the prospect in the research direction of flashover characteristics of train insulators is put porward, and it is believed that the correction of flashover voltage of roof insulators at high altitude and the study of flashover characteristics of actual roof insulators should be focused on, so as to provide theoretical and technical reference for the design and selection of insulators in the Sichuan-Tibet railway engineering.