In view of the hot corrosion status of gas turbine operating under marine environment, the occurrence process and performance characteristics of two types of hot corrosion at high temperature and low temperature were analyzed based on hot corrosion model theory put forward at different stages from the mechanism research on hot corrosion. It was pointed out that hot corrosion was essentially the process of accelerated oxidation caused by the reaction between the dominant Na2SO4 and the metal substrate. On this basis, three kinds of protective coatings were introduced in detail: diffusion coatings, overlay coatings and thermal barrier coatings (TBCs). According to the development stages and functional characteristics of the three coatings, the differences in preparing technique, mechanism and application field were expounded, while the current development of TBCs was emphasized. Based on the representative work of researchers from all over the world, domestic and foreign research progress on gas turbine hot corrosion resistance were systematically summarized. The hot corrosion behavior of metals in sulfate corrosion medium was mainly described and the application of numerical and thermodynamic simulation method in analyzing hot corrosion was presented. Finally, the developing trend of coating technologies for gas turbine is prospected, and it is also proposed that the new generation of environmental barrier coatings (EBCs) is an effective technological means to improve the comprehensive protective performance of gas turbine.