Analyzed　Bayesian　classifier　with　string,　n-gram　and　API　as　features,　we　found　that　it　is　very　difficult　to　improve　Bayesian　classifier　detection　accuracy　because　selected　features　are　not　completely　independent.　In　order　to　solve　this　problem,　we　propose　a　new　improved　choose　features　method　which　are　most　representative　properties,　and　show　that　our　method　achieve　high　detection　rates,　even　on　completely　new,　previously　unseen　malicious　executables.　(C)　2011　Published　by　Elsevier　Ltd.　Selection　and/or　peer-review　under　responsibility　of　[CEIS　2011]