AlCl　3,　NH　3·H　2O,　HNO　2　and　activated　carbon　were　used　as　raw　materials　to　prepare　one　new　type　of　activated　alumina-activated　carbon　composite　material.　The　influence　of　heat　treatment　conditions　on　the　structure　and　property　of　this　material　was　discussed;　The　microstructures　of　the　composite　material　were　characterized　by　XRD,　SEM,　BET　techniques;　and　its　formaldehyde　adsorption　characteristic　was　also　tested.　The　results　showed　that　the　optimal　heat　treatment　temperature　of　the　activated　alumina-activated　carbon　composite　material　was　450　°C,　iodine　adsorption　value　was　441.40　mg/g,　compressive　strength　was　44　N,　specific　surface　area　was　360.07　m　2/g,　average　pore　size　was　2.91　nm,　and　pore　volume　was　0.26　m　3/g.　According　to　the　BET　pore　size　distribution　diagram,　the　composite　material　has　dual-pore　size　distribution　structure,　the　micro-pore　distributes　in　the　range　of　0.6-1.7　nm,　and　the　meso-pore　in　the　range　of　3.0-8.0　nm.　The　formaldehyde　adsorption　effect　of　the　activated　alumina-activated　carbon　composite　material　was　excellent,　much　better　than　that　of　the　pure　activated　carbon　or　activated　alumina,　and　its　saturated　adsorption　capacity　was　284.19　mg/g.