The invention discloses a nitrogen-doped carbon nanotube and sulphur composite material and a preparation method. The preparation method comprises the following steps of: performing carbon nanotube acidification treatment and amine polymerization reaction so as to obtain a bottle-green precursor; putting the precursor in a tubular furnace, and processing under nitrogen atmosphere so as to obtain a nitrogen-doped carbon nanotube; and performing ball-milling and mixing treatment of the nitrogen-doped carbon nanotube and sulphur according to the mass ratio of 1:10 to 3:7 so as to obtain the nitrogen-doped carbon nanotube and sulphur composite material. The nitrogen-doped carbon nanotube and sulphur composite material prepared by the method disclosed by the invention is used in a lithium-sulphur battery, and shows better performance; nitrogen doping has a certain catalysis and adsorption action for breakage and generation of an S-S bond in a charging and discharging process; dissolving of an intermediate product in electrolyte can be reduced; and thus, the nitrogen-doped carbon nanotube and sulphur composite material has better rate and cycle performance.