Al_1–xSc_xN, as a new generation of wurtzite-type ferroelectric material, has become a focal point in ferroelectric materials research in recent years, due to its high remnant polarization, nearly ideal rectangular polarization-electric field hysteresis loops, inherent compatibility with back-end-of-line (BEOL) CMOS processes, and stable ferroelectric phase structure. The systematic and in-depth studies on the preparation, property modulation, and device applications of this material have been conducted. This paper provides a comprehensive review of the research progress of Al_1–xSc_xN ferroelectric thin films. Regarding the factors influencing ferroelectric properties, it emphasizes the regulatory effects of Sc doping concentration on phase transition and coercive field, explores the influences of substrate (such as Si and Al₂O₃) and bottom electrode (such as Pt, Mo, and HfN_0.4) on thin-film orientation, stress, and interface quality, and systematically summarizes the influences of deposition conditions, film thickness, testing frequency, and temperature on ferroelectric performance. At the level of physical mechanisms governing polarization switching, this review elaborates on the domain structure, domain wall motion dynamics, nucleation sites and growth mechanisms in the Al_1–xSc_xN switching process, revealing its microscopic response behavior under external electric fields and the mechanisms underlying fatigue failure. In terms of application prospects, Al_1–xSc_xN thin films show significant advantages in memory devices such as ferroelectric random-access memory (FeRAM), ferroelectric field-effect transistors (FeFETs), and ferroelectric tunnel junctions (FTJs). Their high performance and integration compatibility provide strong technical support for developing next-generation, high-density, low-power ferroelectric memory and nanoelectronic devices.