Covalent　functionalization　of　multi-walled　carbon　nanotubes　(MWCNTs)　were　obtained　through　acidification,　gamma-Methacryloxypropyl　trimethoxy　silane　(KH-570)　treatment,　and　free　radical　polymerization　using　methyl　allyl　polyethenoxy　ether　(HPEG).　Fourier-transformed　infrared　spectroscope　was　employed　to　determine　the　composition　and　structural　changes　of　MWCNTs　after　modification.　The　dispersion　of　MWCNTs　modified　by　HPEG　in　water　at　pH　similar　to　13　was　determined　by　UV-vis-NIR.　In　addition,　the　effects　of　modified　MWCNTs　on　cement　hydration　were　investigated　to　describe　the　dispersibility　of　MWCNTs　in　cement　pastes　indirectly.　Results　show　that　oxygen　functional　groups　generated　on　the　surface　of　MWCNTs　after　acidification　and　KH-570　grafted　on　acidified　MWCNTs　through　Si-O-C　before　radical　polymerization　with　HPEG.　MWCNTs　modified　by　HPEG　exhibit　better　dispersibility　than　pristine　MWCNTs　in　a　simulated　cement　pastes　environment　prepared　at　pH　similar　to　13.　The　additions　of　functionalized　MWCNTs　(P3-S-MWCNTs)　promote　the　hydration　of　cement　pastes　indicated　from　isothermal　conduction　calorimeter　measurement　and　X-ray　diffraction　analysis.　Scanning　electron　microscopy　observation　confirmed　the　good　dispersibility　of　functionalized　MWCNTs　in　cement　pastes.　The　promoting　effect　on　cement　hydration　of　P3-S-MWCNTs　may　attribute　to　the　well-dispersed　MWCNTs.　The　dispersed　MWCNTs　can　act　as　the　nucleating　agent　for　carbon-sulfur-hydrogen　and　carbon-hydrogen,　thus　promoting　the　hydration　of　cement.