The　inert　surface　of　extruded　polystyrene　foam　(XPSF)　was　activated　by　the　ultraviolet-ozone　(UVO)　irradiation,　followed　by　the　surface　coupling　reactions　with　gamma-mercaptopropyl　trimethoxysilane　(MPTMS)　and　vinyl　trie-thylsilane　(VTEO)　to　improve　the　interfacial　affinity　between　the　organic　XPSF　and　inorganic　mortar.　The　re-action　conditions　(including　reaction　time,　concentration　and　pH　of　the　silanes)　were　thoroughly　investigated　in　order　to　reach　the　maximum　bonding　strength　(BS)　of　XPSF/mortar　composites.　It　was　suggested　that　the　presence　of　MPTMS　could　increase　the　BS　value　from　0.04　MPa　to　0.178　MPa　(reaction　time:　10　min,　concen-tration　of　MPTMS:　2%　and　pH　value　of　the　silane　solution:　4).　For　VTEO,　the　maximum　BS　value　reached　to　0.140　MPa　(activation　and　reaction　time:　7　and　3　min,　concentration　of　VTEO:　5%　and　pH　value　of　the　silane　solution:　7).　According　to　the　mechanism　analysis,　the　thiol　groups　in　MPTMS　have　the　strongest　reactivity　with　activated　XPSF　surface　after　UVO　exposure,　leading　to　the　maximized　interfacial　strength　between　the　organic　insulation　materials　and　inorganic　mortar.