Silicide　coatings　and　B-modified　silicide　coatings　were　prepared　on　Nb-Si　based　alloys　using　halide　activated　pack　cementation.　The　hot　corrosion　behavior　of　the　coatings　exposed　to　Na2SO4　2　SO　4　and　Na2SO4　2　SO　4　+　NaCl　mixture　salts　at　900　degrees　C　was　investigated.　The　results　show　that　B-modified　silicide　coatings　possess　better　hot　corrosion　resistance　than　the　silicide　coatings.　The　hot　corrosion　products　of　silicide　coatings　show　a　regional　microstructure,　including　uplift　regions　of　AlNaSiO4　4　imbedded　with　Al2O3　2　O　3　phases,　and　depressed　silica　regions　with　NaNbO3　3　and　TiO2　2　particles.　The　addition　of　B　to　the　silicide　coatings　promotes　the　formation　of　the　uniform　and　dense　boroaluminosilicate　scale　with　better　fluidity　during　hot　corrosion,　which　impedes　the　self-sustaining　cyclic　chlorination/sulfidation　reactions,　and　thus,　improves　the　hot　corrosion　resistance　of　the　silicide　coatings.