The invention relates to environment-friendly waterproof 
coating and a preparation method thereof. The 
coating comprises two parts: a component A, namely a superhydrophobic material, and a component B, namely a 
coating composition, wherein the component A, namely the superhydrophobic material, is prepared from the following components in parts by 
mass: 15 to 25 parts of 
graphene, 2.5 to 6 parts of a water-soluble cationic surfactant, 55 to 75 parts of a 
sodium silicate solution, 10 to 15 parts of 10% NaOH, 25 to 45 parts of a silanizing 
reagent and 8 to 15 parts of deionized water; the superhydrophobic material is obtained by performing silanizing treatment on the surface of the 
graphene by an electrochemical lamination method; the component B, namely coating composition, is prepared from the following components in parts by 
mass: 20 to 30 parts of 
lignin, 20 to 30 parts of 
starch, 16 to 18 parts of 
diatom ooze, 10 to 12 parts of ash 
calcium, 11 to 15 parts of ground 
calcium carbonate, 0.5 to 1 part of a defoaming agent, 0.8 to 1 part of a dispersing agent and 15 to 30 parts of deionized water; and the waterproof coating is prepared by mixing the component A, namely the superhydrophobic material, and the component B, namely coating composition. According to the environment-friendly waterproof coating and the preparation method thereof which are provided by the invention, environment-friendly 
biomass materials, such as the 
starch, the 
lignin, the 
diatom ooze and the like, are adopted, and the added superhydrophobic material makes up the defect that the 
diatom ooze and 
calcium powder absorb 
moisture easily, so uniform and excellent 
water resistance of the coating layer is achieved.