Effect　of　heat　treatment　on　microstructure　and　hardness　of　Al0.5CoCrCuFeNi　high　entropy　alloy　prepared　by　water　cooled　copper　crucible　vacuum　induction　levitation　melting　was　investigated.　The　results　show　that　the　phase　character　of　the　as-prepared　sample　is　simple,　which　composes　of　two　kinds　of　FCC　structures　with　different　compositions,　poor　Cu　FCC1　phase　in　the　dendrite,　Cu　rich　FCC2　phase　between　the　interdendritic,　and　its　microstructure　consists　of　dendrite　with　dendrite　segregation.　Hardness　of　the　as-prepared　samples　exceeds　255　HV0.5.　The　alloy　has　good　thermal　stability,　with　the　increase　of　heat　treatment　temperature,　the　phase　structure　and　hardness　of　the　alloy　are　considerably　stable.　Microstructure　and　phase　structure　of　the　alloy　keep　stable　by　different　cooling　method,　but　the　hardness　of　the　alloy　after　furnace　cooling　is　higher　than　that　of　those　after　air　cooling　and　water　cooling.　©　2015,　Chinese　Mechanical　Engineering　Society　of　Heat　Treatment.　All　right　reserved.