Inorganic phosphate-based composite coatings are widely used in military high-tech fields of aerospace and civil industrial fields due to their excellent high-temperature resistance, nuclear/space-resistant irradiation and good compatibility with special media. The types of inorganic phosphate-based composite coatings were introduced in detail based on binders with different structures prepared by various metal ions of different types and radius sizes. Besides, the bonding properties, heat resistance and storage stability of inorganic phosphate-based adhesives were described and compared, and their respective advantages and weaknesses were outlined in detail. The current application of inorganic phosphate-based composite coatings in the field of high temperature protection, corrosion protection, lubrication protection, space coupling irradiation and ground strong radiation environment was comprehensively summarized. The protective mechanisms of inorganic phosphate-based composite coatings under different service conditions were also described. In view of the problems faced by the application of inorganic phosphate-based composite coatings in different fields, some technical means and methods to further improve the properties of inorganic phosphate-based composite coatings were proposed. In particular, considering the unique properties of inorganic phosphate-based composite coatings, such as excellent radiation resistance, high temperature resistance, good space environment adaptability and weather resistance, the key scientific and technical issues that need to be solved in the surface protection of high-tech industries like aerospace, weapons and nuclear technology were discussed, and their development trends were also prospected.