Epoxy　resin　(EP)　has　widespread　applications　in　thermosetting　materials　with　great　versatility　and　desirable　properties　such　as　high　electrical　resistivity　and　satisfactory　mechanical　properties.　At　present,　9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide　(DOPO)　is　widely　applied　to　EP　matrix　for　high　flame　resistance.　Nevertheless,　EP/DOPO　composites　acquire　highly　toxic　decomposition　products　and　smoke　particles　produced　during　combustion　due　to　the　gaseous　fire-inhibition　mechanism,　which　will　be　a　major　problem.　To　address　this　concern,　an　effective　hyper-branched　aluminum　phosphonate　(AHPP)　was　rationally　designed　and　then　coupled　with　DOPO　into　EP　matrix　to　fabricate　the　fire-safe　epoxy　resin　composites.　On　the　basis　of　the　results,　significant　increment　in　limiting　oxygen　index　value　(an　achievement　of　32%　from　23.5%　for　pristine　EP)　and　reduction　in　peak　heat　release　rate　and　total　heat　release　(59.4%　and　45.6%)　with　the　DOPO/AHPP　ratio　of　2:1　were　recorded.　During　the　cone　calorimeter　test,　both　the　smoke　production　and　total　CO　yield　of　EP-4　composite　with　the　DOPO/AHPP　ratio　of　1:2　were　dramatically　decreased　by　42.7%　and　53.6%,　which　was　mainly　associated　with　the　excellent　catalytic　carbonization　of　AHPP　submicro-particles　for　EP　composite.　Future　applications　of　submicro-scaled　flame-retardant　with　various　phosphorus　oxidation　states　will　have　good　prospects　for　development.　©　2019　by　the　authors.　Licensee　MDPI,　Basel,　Switzerland.