Taking　advantages　of　excellent　adhesion　and　insulating　properties,　polymer-based　thermal　interface　materials　have　been　widely　used　in　electrical　and　electronic　industry.　However,　applications　was　limited　due　to　the　existence　of　high　interfacial　resistance　and　poor　mechanical　properties　resulted　from　poor　dispersion　and　weak　interfacial　adhesion　of　thermal　conductive　fillers　in　the　polymer　matrix.　Herein,　different　sizes　of　aluminum　oxide　microparticle　was　used　as　thermal　conductive　fillers　to　fabricate　a　series　of　high　thermal　conductive　epoxy　composites,　and　the　effect　of　fillers　loading　ratio　on　the　properties　of　thermal　conductive,　mechanical,　thermal　stability　was　further　analyzed.　The　optimum　composite　exhibits　a　high　thermal　conductivity　(1.91　+/-　0.02　W　center　dot　m(-1)center　dot　K-1)　at　a　loading　ratio　of　1:　2　(20-mu　m:　70-mu　m,　mass　ratio),　which　is　equivalent　to　a　thermal　conductivity　enhancement　of　950%　in　comparison　with　pure　epoxy　resin.　The　outstanding　properties　of　the　as-prepared　composite　is　mainly　attributed　to　the　effective　conductive　network　formed　by　different　size　fillers　that　the　smaller　particles　act　as　a　bridge　to　connect　the　larger　one.　This　work　has　proved　by　Agari　model　that　combining　different　sizes　Al2O3　as　fillers　is　a　workable　way　to　obtain　composite　with　high　thermal　conductivity　and　it　is　expected　to　provide　a　reliable　route　for　the　preparation　of　thermally　conductive　composites　with　different　particle　sizes.