With the development of emerging technologies such as dynamic infrared stealth and intelligent thermal control, it is gradually difficult for a single low-emissivity material to meet the complex needs of practical applications. The infrared emissivity of variable emissivity materials can be reversibly changed under certain conditions. In this paper, the research progress of thermo-emissivity, electro-emissivity, and other variable emissivity materials such as stress-induced and humidity-induced materials is systematically summarized according to the different applied fields that induce the infrared emissivity transition. In this paper, the principles and practical applications of vanadium dioxide (VO₂) in thermally variable emissivity materials and tungsten trioxide (WO₃) and polyaniline (PANI) in electro-variable emissivity materials are discussed, and the performance characteristics of various materials are summarized and analyzed. The research on variable emissivity materials has greatly promoted the development of adaptive infrared stealth technology, and has been widely used in the fields of intelligent thermal control and urban energy conservation, and will be developed in the direction of fast response, long life and multi-spectral modulation in the future.