The　influence　of　the　addition　of　two　carbon　nanotubes　(CNTs),　namely,　multiple-wall　carbon　nanotubes　(MWNT)　and　OH-functionalized　MWNT,　on　the　carbonization　behavior　of　coal-tar　pitch　was　studied.　The　mixtures　of　coal-tar　pitch　and　CNTs　were　prepared　by　ultrasonic-assisted　dispersion　in　liquid　phrase.　The　thermal　behavior　of　the　mixtures　was　studied　by　thermogravimetric　analysis　(TGA).　In　addition,　the　optical　texture　and　micro-crystal　structure　of　resultant　cokes　produced　from　carbonization　of　the　mixtures　were　characterized　by　reflected　polarized　light　microscopy　and　X-ray　diffraction　(XRD),　respectively.　The　results　show　that　the　thermal　stability　of　coal-tar　pitch　increases　with　the　addition　of　CNTs,　indicated　by　that　the　weight　loss　temperature　and　coke　value　is　improved.　Moreover,　the　addition　of　CNTs　contributes　to　the　formation　of　large　anisotropic　unit　in　some　regions　of　the　optical　texture,　which　results　in　an　increase　in　the　heterogeneity　of　the　micro-crystal　structure　of　resultant　cokes.