The work aims to solve fouling problem existing in boiler burning high-alkali coal by studying fouling resistance of composite ceramic coating to high-alkali coal. With water wall material 20G and superheater material TP347 as study objects, composite ceramic coating was prepared on the surfaces in slurry method. SEM and EDS were used to observe and analyze microstructure of the samples after experiment, and study fouling resistance of the coating to Na2SO4, K2SO4 and Zhundong ash. The surface of composite ceramic coating was dense after sintering and curing, and was well bonded to the substrate. After 120 h fouling test of Na2SO4, K2SO4 and Zhundong ash, fouling rate of uncoated 20G and TP347 steel sheet samples was 20.31%, 13.33%, 32.31% and 16%, 10%, 29%, respectively, and that of coated 20G and TP347 steel sheet samples was 0.38%, 0.26%, 0.75% and 0.26%, 0.13%, 0.39%, respectively, essentially 0%. Some subtle Na2SO4, K2SO4 and Zhundong coal ash particles might easily adhere to slice oxide film structure on the surface of uncoated sheet samples, some microcracks on the coating might also hold up fine particles in crack area. And the fine particles could hardly be removed by air blowing with compressed air. Composite ceramic coating prevented sediment from directly contacting with the steel substrate, exhibited lower surface energy and chemical incompatibility, thus the sediment was of low adhesivity and certain fouling resistance to high-alkali coal.