The invention discloses a coating method of a civil defense door coating. The coating method comprises the following steps: step 1, detecting the internal structure of a civil defense door, and afterthe detection result is qualified, grinding and cleaning the surface of the civil defense door by a laser cutting device to enable the surface to be flat and has no impurity; step 2, preparing an organic coating according to the following materials in parts by mass: 20 parts of halogenated butyl rubber, 12 parts of chlorinated butyl rubber, 10 parts of sodium silicate, 3 parts of mica powder, 8 parts of zirconium oxide, 5 parts of titanium dioxide, 2 parts of zinc phosphate and 15 parts of modified organic resin; and step 3, spraying the prepared organic coating on carbon fiber cloths, and then laying the carbon fiber cloths on the front face and the back face of the civil defense door, wherein the carbon fiber cloths are laid for multiple layers. The coating method of the civil defense door coating can notably increase the impact resistance and the service life of the civil defense door, and can prevent moisture, mildew and oxidation.