It　is　generally　accepted　that　the　crack　is　appeared　when　the　thermal　stress　is　accumulated　which　caused　by　the　mismatch　of　coefficient　of　thermal　expansion,　through　which　oxygen　will　severely　destroy　the　substrate　at　high　temperature　environments.　Therefore,　the　coatings　with　gradient　structure　to　reduce　thermal　expansion　mismatch　should　greatly　improve　their　service　stability.　Here　AleY　gradient　coating　is　prepared　on　gamma-TiAl　alloy　by　magnetron　sputtering.　The　results　show　that　the　hot　corrosion　resistance　of　gamma-TiAl　alloy　could　be　greatly　improved,　and　the　activation　energy　at　(750　degrees　C-950　degrees　C)　can　be　calculated　to　be　126.88　KJ/mol　for　the　coating.　The　Al2O3　and　Y3Al5O12　(YAG)　are　the　primary　phases　after　hot　corrosion,　thus　providing　efficient　protection　at　750,　850　degrees　C.　At　950　degrees　C,　the　consumption　of　oxide　layers　is　accelerated　due　to　the　increased　temperature　so　that　some　corrosive　elements　(such　as　S　and　Na)　unavoidably　invade　into　the　scale.　The　improvement　of　hot　corrosion　resistance　primarily　owes　to　the　existence　of　Y　preferentially　oxidizes　Al　to　form　alpha-Al2O3,　and　the　effect　of　grain　refinement　of　YAG　phases.