Hexagonal boron nitride (h-BN) has excellent thermal stability, barrier property, high temperature resistance, and other properties, so it has been widely concerned by researchers all over the world. It is helpful to improve the performance of anti-corrosion coatings by introducing h-BN into the current anti-corrosion coatings system, so it has become one of the research hotspots in the field of anti-corrosion coatings. The physical and chemical properties of h-BN and its nanocomposites (BNNSs) are introduced firstly. Then, the “top-down” and “bottom-up” preparation methods of BNNSs are introduced, and their advantages and disadvantages are analyzed and compared. The research progress to prepare BNNSs is summarized in combination with the widely used ultrasonic assisted liquid phase stripping technology, and the emerging BNNSs preparation strategies in recent years are introduced. The “dispersion” and “compatibility” of h-BN applied in anti-corrosion coatings are the primary problems to be solved at present. The functional modification of h-BN can effectively to improve the dispersion of BNNSs in the coating system and the compatibility of h-BN in anti-corrosion coatings. Therefore, the modification methods of “covalent functionalization” and “non-covalent functionalization” are analyzed, compared and summarized, and the new technology to prepare functional BNNSs by plasma gas modification are also introduced. After that, the application progress of h-BN in anti-corrosion coatings is introduced by combining with epoxy coatings, polyurethane coatings, and acrylic acid coatings widely used in the field of the anti-corrosion coatings, and the anticorrosive mechanism of its reinforced coatings is also explained in combination with the relevant research progresses. Finally, based on the current application status of h-BN in the field of the anti-corrosion coatings, relevant suggestions are put forward for the future research focus.