The　accurate　prediction　of　cyberspace　situation　is　fundamental　to　intrusion　prevention　in　large　scale　networks.　After　analyzing　the　cyberspace　situation,　a　cyberspace　situation　prediction　model　based　on　gene　expression　programming　(GEP-CSP)　is　proposed,　to　predict　the　time　series　of　cyberspace　situation.　Besides,　since　its　own　intrinsic　characteristics,　GEP-CSP　solves　the　problem　that　the　traditional　time　series　methods　can＇t　make　an　accurate　prediction　without　the　pre-knowledge.　By　employing　GEP-CSP,　the　experiments　on　Abilene　network　flow　data　reached　the　expectation　and　made　a　precise　prediction.　©　2009　IEEE.