The invention relates to the field of building coatings and provides a water-based conductive electromagnetic shielding building coating based on graphene. The defects that a coating in the prior art is poor in electromagnetic wave shielding performance in the frequency bands of 100 KHz to 1 GHz, short in expiry date, poor in adhesive force for a base material and poor in cold and hot cycle resistance are overcome. The water-based conductive electromagnetic shielding building coating is prepared from, by weight, 1-3 parts of antifreezing agent, 0.1-0.2 part of neutralizer, 0.1-0.3 part of wetting agent, 0.1-1 part of dispersant, 0.1-0.5 part of defoamer, 1-5 parts of graphene, 35-50 parts of calcium carbonate, 0.1-0.3 part of preservative in a tank, 0.1-0.3 part of dry film mould-proof anti-algae agent, 1-3 parts of coalescing agent, 1-2 parts of thickener, 15-25 parts of emulsion and the balance deionized water.