The amorphous, .-GeTe, and .-GeTe phases of GeTe can be stably converted to each other under certain conditions. Because doping-based high-concentration holes can improve the thermoelectric and ferroelectric performances of GeTe, and it can be converted quickly between its amorphous and crystalline phases, GeTe has been applied to thermoelectric devices, spintronic devices, phase change switches, phase change memory, and others. Moreover, GeTe has a narrow optical band gap and high carrier mobility, which is expected to contribute positively to the development of high-performance infrared detectors. However, its application in the infrared detector field is still new. In this paper, its physical characteristics and its applications in areas including the thermoelectric, spintronic, and phase transition fields are reported. Based on its photoelectric properties, its application in the infrared detector field is expected.