Abstract: Long-runout rockslides at high altitude have caused lots of severe casualties and huge economic losses in the world, becoming a focus issue in researches on mitigation for large-scale geological disasters. This paper systematically reviews the research process of high-altitude and long-runout rockslides and believes that conventional research on “high velocity and long runout” is difficult to adapt to the requirements of complex geohazards prevention and mitigation in high and extra-high mountains. The methodology on high-altitude and long-runout rockslides has been proposed that includes in the initiation at the high-position, the dynamics of chain-style disasters with a long-runout traveling and the risk assessment and mitigation. Then, the disaster-prone geostructure characteristics and early identification techniques of the high-altitude initiation zone, the long-runout transferring mechanism and boundary layer effect of high-velocity debris avalanche, and risk assessment and mitigation issues have been explored. Through the study in the high mountain and extra-high mountains of the Qinghai-Tibet Plateau indicates that the potential flow transferring mechanism of debris avalanche in high-altitude rockslides, the boundary layer effect of turbulent fluid and the plowing bodies. It is proposed that energy dissipation and risk mitigation methods can be used by modifying the boundary layer bottom slope of high potential debris avalanche, to increase the generation of turbulent kinetic energy in the boundary layer, and the dead zone range in front of barrier piles. Three research directions have been discussed, including the initiating mechanism of disaster-prone geostructure, the dynamic process of high-altitude and long-runout disaster chains, and the theory and technology of risk prevention and mitigation.