Conducting microtubules of Polyaniline (PANI) were synthesized for the first time by the "in situ doping polymerization" method in the presence of p-naphthalenesulfonic acid (NSA) as dopant. Different doping methods, such as "immerse doping＇＇ and "grind doping," and different synthetic conditions, such as molar ratio of aniline (An) to NSA (An/NSA), concentration of NSA in the polymerization media, reaction temperature, and time were investigated to understand the formation of microtubules. it was found that the PANI-NSA microtubules can be formed only by the "in situ doping polymerization" method, and the above synthetic conditions strongly affect the formation of the PANE-NSA microtubules, especially the molar ratio of An to NSA. An optimal condition was found under which tubules with 1-3 mu m in diameter and 10-50 mu m in length were obtained. The morphology of PANI-NSA tubules was proved by SEM and TEM, and their backbone structure was characterized by FTIR, W-VIS, XPS, and X-ray diffraction. Results of these measurements showed that the molecular structures of the resulted PANI-NSA microtubules were identical to that of PANI-HCl synthesized by conventional method.