The invention discloses an amido reinforced graphene fiber and a preparation method thereof. The method includes the following steps: staying a graphene oxide solution in a mixed liquid of amine solidification liquid and a reducing agent for solidification, reduction and self-assembly into a graphene hydrogel in a manner of extrusion through a spin duct; and drying to obtain amido reinforced graphene fiber, 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 realizes solidification, reduction and self-assembly into amido reinforced graphene fiber 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 fiber prepared by the method has good strength and toughness, and excellent thermal conductivity and electrical conductivity.