Alumina　adsorbent　was　synthesized　from　waste　aluminum　sludge　in　this　research.　The　nitrogen　isothermal　adsorption　method　(77K)　is　applied　to　measure　the　BET　specific　surface　area　and　pore　structure　of　activated　alumina　at　different　activation　temperatures.　The　research　results　indicate　that,　thermal　treatment　has　huge　influences　on　the　test　sample＇s　specific　surface　area　and　pore　structure.　Its　specific　surface　area　and　pore　volume　expand　and　then　diminish,　whereas　the　holding　time　rises,　getting　its　peak　of　348　m(2)/g　and　0.55　(cm(3)/g)　respectively　at　the　activation　temperature　of　600　degrees　C　and　holding　time　for　1　hour.　The　average　pore　diameter　value　increases　along　with　the　lengthening　of　activation　temperature　and　holding　time,　reaching　the　maximum　of　11nm　at　activation　temperature　of　750　degrees　C　and　holding　time　for　4　hours.　After　comprehensive　analysis,　the　activation　temperature　of　600　degrees　C　and　holding　time　for　1　hour　are　determined　as　ideal　conditions　for　activated　alumina　respectively.