Two　groups　of　RF-sputtered　BN　films　(pure　hexagonal　phase　and　approximately　27.5%　cubic　content,　respectively)　were　annealed　at　600　to　1000　°C　under　nitrogen　at　atmospheric　pressure　after　deposition.　FTIR　spectroscopy　indicates　a　reversible　transformation　from　hexagonal　phase　to　cubic　phase,　and　again　hexagonal　phase.　The　most　effective　temperature　for　h-BN　converting　to　cubic　zincblende　(c-BN)　is　900　°C.　Further,　the　indirectly　stepwise　transformation　from　hexagonal　(h-BN)　to　explosive　BN　(E-BN)　and　then　to　c-BN　employing　metastable　E-BN　as　an　intermedium　was　observed.　In　addition,　we　tentatively　put　forward　that　the　existence　of　defective　h-BN　and　the　N　defects　plays　a　key　role　on　h-BN　to　c-BN　transformation.　©　2008　Elsevier　B.V.　All　rights　reserved.