The invention discloses a method for preparing nitrogen-doped graphene with high nitrogen doping amount. The method comprises the following steps: (1) dispersing of graphene; (2) ultrasonic dispersion; (3) microwave heating; and (4) filtering and drying. The nitrogen doping amount of the nitrogen-doped graphene prepared by the method disclosed by the invention is 10%-15.0%, the density of free carriers in graphene is greatly increased by the high nitrogen doping amount, the interaction of graphene and metal is enhanced, no oxidation pretreatment is carried out, no toxic solvent is used in the reaction process, reactants are simple in component, reaction conditions are mild, and the prepared nitrogen-doped graphene has excellent electrochemical property and can be used for preparation of new energy materials such as lithium ion battery, lithium-air battery, super capacitor electrode material and fuel cell oxygen reduction catalysts. According to the method disclosed by the invention, a high-pressure kettle is heated by using microwaves without high temperature; the method is low in energy consumption, is carried out in an airtight environment and therefore hardly causes environment pollution; in addition, the method is simple in process and convenient to operate and needs less production equipment, thus, the cost is further reduced.