The invention belongs to the technical field of new materials, and discloses a direct writing supercapacitor and a preparation method and an application thereof. The capacitor is prepared by the following steps of performing mixing on carbon nano tubes, nano-silver, a dispersing agent and water according to a certain ratio, and then carrying out ball milling to obtain ink of a writing capacitor; then injecting the ink into a water absorption cotton strip of a blank sign pen or a refill of a blank ballpoint pen, and performing assembling to obtain a pen of the writing capacitor; enabling the pen to be mounted on a plotting instrument, performing electrode drawing on a flexible substrate, wherein the size of the drawn pattern can be adjusted according to needs; and enabling the drawn electrodes to be dried naturally in the air, and coating the two electrodes and the upper surface of the flexible substrate between the two electrodes with a layer of electrolyte to obtain the direct writingsupercapacitor. The method has the advantages that the preparation process is simple, the problem of nozzle blocking in ink-jet printing is solved, a plane capacitor which can directly write on paperis obtained, re-assembling is not needed, and uncertainty of the quality and performance of the manufactured capacitor is effectively avoided.