The invention discloses a preparation method and device for wrapping metal wires with carbon nanomaterials. The preparation method comprises the following steps: the metal wires are neatly arranged and bundled together to form capillary tubes, then the capillary tubes are soaked in a suspension containing the carbon nanomaterials, after being taken out, the capillary tubes are subjected to evaporation drying, the soaking, the taking-out and the evaporation drying of the capillary tubes can be repeated, and then the metal wires bundled together are separated to obtain the metal wires wrapped with the carbon nanomaterials; the metal wires arranged neatly and bundled together and wrapped with the carbon nanomaterials are soaked in a graphene suspension again, and then the metal wires bundled together are separated to obtain metal wires sequentially wrapped with carbon nano tubes and grapheme; the metal wires are neatly arranged and bundled together and soaked into a carbon nano tube and grapheme mixed suspension, and are subjected to evaporation drying, the soaking, the taking-out and the evaporation drying of the metal wires can be repeated for multiple times, and then the metal wires bundled together are separated to obtain metal wires wrapped with the carbon nano tubes and grapheme. The method is simple, is easy to realize industrial production and has very wide application prospects in the fields, such as electromagnetic shielding, conducting cables, flexible electronic devices, intelligent textiles, solar devices, energy storage batteries, and linear supercapacitors.