The invention discloses water-based graphene / carbon nanotube composite electric-heating conversion printing ink and a preparation method thereof. The preparation method comprises the following steps: uniformly stirring a graphene microchip, a water-based non-ionic high-polymer dispersant and water, and then dispersing so as to obtain a first dispersion; putting one-dimensional nano-powder into inorganic strong acid, carrying out heating reflux, carrying out ultrasonic treatment, washing with water, and drying, so as to obtain a second dispersion; uniformly mixing the second dispersion with carbon black powder, a water-based anionic dispersant, sodium dodecyl benzene sulfonate, a water-based hydroxyl-modified nano-acrylic emulsion and dimethylethanolamine, and then dispersing so as to obtain a third dispersion; and mixing the first dispersion, the third dispersion and water-based resin, grinding, adding a flatting agent, a defoamer, a pH adjusting agent, a preservative and an anti-settling agent, and uniformly mixing, so as to obtain the water-based graphene / carbon nanotube composite electric-heating conversion printing ink. The invention further discloses the water-based graphene / carbon nanotube composite electric-heating conversion printing ink.