The invention provides a preparation method of high-specific-surface-area nitrogen doped grapheme by adopting a microwave vacuum high-temperature heating furnace. The preparation method includes the steps of 1), preparing grapheme oxide (2) by a Hummers method and performing in-situ microwave treatment, thermal reduction and chemical vapor deposition (CVD) doping of the grapheme oxide. In-situ operations of microwave prestripping and thermal reduction before thermal reduction and chemical vapor deposition doping after thermal reduction of the grapheme oxide are realized on the premise of self-improvement of equipment, synthetic efficiency is increased, energy consumption of synthesis is lowered, and the preparation method is suitable for industrial mass production. The doped grapheme obtained in synthesis can be used in fields of electrochemical catalysis, supercapacitor and the like.