The invention discloses a preparation method of a nitrogen-doped graphitized carbon material, and the method comprises the following steps: respectively taking tannic acid, urea and zinc chloride as acarbon source, a nitrogen source and an activating agent, taking water as a solvent, mixing raw materials into a suspension, reacting in a drying oven for a certain time, and calcining an obtained solid sample in a nitrogen atmosphere to obtain a graphitized carbon material. The nitrogen-doped graphitized carbon material prepared by the invention has rich pore structures and surface adsorption active sites and can be used as an efficient absorbent for adsorbing CO2 and dyes, and the preparation method of the nitrogen-doped graphitized carbon material disclosed by the invention takes the tannic acid and urea which are rich in sources and environment-friendly as raw material substances and takes the water as the solvent. The whole preparation process is simple, the synthesis method is low in temperature and cost, equipment is simple and easy to operate, and regeneration is easy and convenient.