Magnesium　oxide　(MgO)　and　MgO/Al2O3　composite　thin　films　were　prepared　on　silver　substrates　by　DC　magnetron　sputtering　technique　and　their　secondary　electron　yields　(delta)　and　working　durability　under　constant　electron　bombardment　were　investigated.　X-ray　photoelectron　spectroscopy　and　Auger　electron　spectroscopy　analyses　reveal　that　uniform　MgO/Al2O3　composite　films　were　developed　and　residual　Al　exists　in　the　films　after　sputtering　of　the　Mg-Al　alloy　in　an　Ar-O-2　mixed　atmosphere　on　silver　substrates　heated　at　400A　degrees　C.　The　MgO/Al2O3　composite　films　show　superior　delta　as　high　as　11.6　and　much　better　resistance　to　electron　bombardment　than　that　of　pure　MgO　films.　Good　secondary　electron　emission　(SEE)　properties　of　the　MgO/Al2O3　film　are　probably　due　to　the　presence　of　alumina　in　the　film,　which　has　higher　bond　dissociation　energy　than　MgO,　as　well　as　the　presence　of　residual　Al　in　the　film,　which　contributes　to　effective　electron　transport　in　the　film　and　diminished　surface　charging　during　SEE.　With　superior　SEE　performance,　MgO/Al2O3　films　have　potential　for　practical　electron　multipliers　in　various　vacuum　electron　devices.