The present invention discloses an amido reinforced graphene film, a nitrogen doped graphene film and a preparation method thereof. The method includes the following steps: extruding a graphene oxide solution by a device with an in-line die orifice nozzle; staying, solidifying and reducing in a mixed liquid of liquid amine solidification liquid and a reducing agent for self-assembly into a film, and drying, wherein the temperature of the mixed liquid is 60-95 DEG C, and the stay time is more than 0.5 h. The method has the wide raw material sources and low cost; the preparation method uses graphene oxide solution as raw material, realizes solidification, reduction and self-assembly into amido reinforced graphene film through one step, has the advantages of low reaction temperature, simple operation, green and environment-friendliness, and can realize large-scale continuous preparation. The amido reinforced graphene film prepared by the method has good strength and toughness, excellent thermal conductivity and electrical conductivity, and broadens the scope for subsequent application. The amido reinforced graphene film can increase the electrical conductivity and mechanical properties of the film.