Abstract: With the continuous development of cutting-edge science and new technologies, the studies on the ultra-conventional scale, density, hardness, stiffness and other properties of engineering materials and structures, as well as their mechanical behavior in extreme environments, such as ultra-conventional temperature, speed, physical and chemical fields, and severe weather, requires more effective theories and methods of mechanics. This presentation starts from the fundamental definition and scientific connotation of extreme mechanics, introduces the research status of extreme mechanics from three aspects: extreme properties, extreme loads, and discipline development, in combination of grand engineering and scientific challenges. The characteristics of extreme mechanics and major challenges in the aspects of mechanical theory, computational methods and experimental techniques are concluded. Prospects for the future development of extreme mechanics are proposed.