The present invention relates to a method for preparing carbon nanotubes, the method including: preparing a support including AlO(OH) by primary heat treatment of Al(OH)3; preparing an active carrier by supporting a mixture including a main catalyst precursor and a cocatalyst precursor on the support; drying the active carrier through multi-stage drying including vacuum drying; preparing a supported catalyst by secondary heat treatment of the dried active support; and preparing carbon nanotubes in the presence of the supported catalyst, and the carbon nanotubes prepared by the method as described above can remarkably improve conductivity.