Abstract: Soft magnetic composites (SMCs) have emerged as critical materials in high-frequency power electronics due to their superior high-frequency low-loss characteristics and three-dimensional formability. Among them, FeSiCr and Fe-based amorphous/nanocrystalline soft magnetic composites represent the current mainstream systems. As a core processing step, the insulating coating technology directly determines their comprehensive properties, including electrical resistivity, permeability, core losses, and mechanical stability. This review systematically examines the compositional design, fabrication processes, and application-specific adaptability of three categories of alloy powders, with a focused analysis of inorganic, organic, and hybrid inorganic-organic coating methodologies for corresponding SMCs. It further elaborates on material systems, processing routes, and their underlying mechanisms governing microstructure evolution and macroscopic performance. By comparing the effects of various coatings on eddy current suppression, thermal stability enhancement, and interfacial bonding, we reveal the nonlinear coupling relationships among coating thickness, uniformity, and magnetic properties. Additionally, we introduce advanced characterization techniques for evaluating coating effectiveness, offering theoretical foundations and technical references for the engineered development of high-performance SMCs.