A　novel　metal-organic　framework　(MOF)-based　electroactive　nanocomposite　containing　graphene　fragments　and　HKUST-1　was　synthesized　via　a　facile　one-step　solvothermal　method　using　graphene　oxide　(GO),　benzene-1,3,5-tricarboxylic　acid　(BTC),　and　copper　nitrate　(Cu(NO3)2)　as　the　raw　materials.　The　morphology　and　structure　characterization　revealed　that　the　GO　could　induce　the　transformation　of　HKUST-1　from　octahedral　structure　to　the　hierarchical　flower　shape　as　an　effective　structure-directing　agent.　Also,　it　is　interesting　to　find　out　that　the　GO　was　torn　into　small　fragments　to　participate　in　the　formation　of　HKUST-1　and　then　transformed　into　the　reduction　form　during　the　solvothermal　reaction　process,　which　dramatically　increased　the　surface　area,　electronic　conductivity,　and　redox-activity　of　the　material.　Electrochemical　assays　showed　that　the　synergy　of　graphene　and　HKUST-1　in　the　nanocomposite　leaded　to　high　electrocatalysis,　fast　response,　and　excellent　selectivity　toward　the　reduction　of　hydrogen　peroxide　(H2O2).　Based　on　these　remarkable　advantages,　satisfactory　results　were　obtained　when　the　nanocomposite　was　used　as　a　sensing　material　for　electrochemical　determination　of　H2O2　in　the　complex　biological　samples　such　as　human　serum　and　living　Raw　264.7　cell　fluids.　©　2016　American　Chemical　Society.