Poly(p-phenylene benzobisthiazole) (PBZT) Was crystallized from dilute solution in the presence of single-wall carbon nanotube (SWNT) or multi-wall carbon nanotube (MWNT). In this crystallisation condition, SWNT existed as pristine bundles. SWNT bundles and MWNT acted as nucleating agents of PBZT crystallisation.The nucleating effect of the SWNT bundle was larger than that of MWNT. Transmission electron microscope observation revealed that the morphology of the PBZT crystal on the carbon nanotube (CNT) could be controlled by crystallization condition such as molecular length of PBZT, H2SO4 concentration, variety of CNT. Thermal stability of PBZT crystallized on SWNT bundles was discussed by the observation of crystal dissolution temperature.