The invention discloses a preparation device and a preparation method of a metallic aluminum coating on the surface of a carbon fiber. The device comprises a molding device for molding an aluminum coating on the surface of the carbon fiber, wherein a cooling device for cooling the carbon fiber coated with the aluminum coating is arranged at the lower side of the molding device; a collection device for collecting the carbon fiber coated with the n aluminum coating is arranged at the lower side of the cooling device; the molding device comprises a melt tank and a thermal insulation plate; a plurality of axial through holes through which the carbon fiber passes are uniformly formed in the side wall of the melt tank; a discharge hole is arranged between the axial through holes and the inside of the melt tank; an overflow opening is arranged between the axial through hole and the melt tank; and a feeding hole and a pressurizing hole are formed in the top of the melt tank. Fast and continuous preparation of the aluminum coating on the surface of the carbon fiber can be achieved by controlling the drawing rate of the fiber and the extrusion pressure of molten aluminum; the contact time of the carbon fiber and the molten aluminum is shortened; and reduction of the mechanical property of the carbon fiber is effectively prevented.