Porous　carbons　were　prepared　by　pyrolysis　of　the　mixture　of　coal-tar　pitch　and　nano-MgO,　and　the　effect　of　carbothermal　reduction　between　nano-MgO　and　carbons　on　their　microstructures　was　studied.　Pyrolysis　behavior　of　the　mixture　was　characterized　by　simultaneous　thermogravimetry–differential　scanning　calorimetry　(TG–DSC)　and　X-ray　diffraction　(XRD).　In　addition,　the　microstructures　of　resulting　porous　carbons　were　studied　using　scanning　electron　microscopy　(SEM),　transmission　electron　microscopy　(TEM),　Raman　spectroscopy　and　nitrogen　adsorption-desorption　measurement.　Results　show　that　the　carbothermal　reduction　occurs　when　the　temperature　is　beyond　1300 °C,　greatly　influencing　the　microstructures　of　the　resulting　porous　carbons.　With　the　increasing　of　temperature,　the　porous　carbon　prepared　possesses　a　thinner　thickness　of　pore　wall　and　a　higher　specific　surface　area　with　a　less　mesopore　volume.　When　the　temperature　arrives　at　1800 °C,　the　porous　carbon　prepared　exhibits　three-dimensional　network　structures　consisting　of　few-layered　graphene　sheets.　©　2017　Elsevier　B.V.