The invention discloses a nano water-based functional ceramic composite coating which comprises raw materials in parts by weight as follows: 10-35 parts of silicate inorganic adhesives, 10-35 parts of main filler, 2-10 parts of stabilizing materials, 5-20 parts of toughness-enhancing emulsion type binding agents, 3-10 parts of film forming assistants and 5-25 parts of water. A preparation method comprises the steps as follows: the silicate inorganic adhesives and diluent are poured into a container and stirred at 350-400 r/min for 10-20 min, so that a mixed liquid is obtained; the main filler and the stabilizing materials are added to the mixed liquid, and the mixture is stirred at 350-400 r/min for 50-60 min; and the toughness-enhancing emulsion type binding agents and the film forming assistants are added sequentially, and the mixture is filtered by gauze with 400-600 meshes, so that the composite coating is obtained. A film of the coating is formed at the normal temperature, and the nano water-based functional ceramic composite coating has the characteristics of infiltration, large adhesive force, high density, stone hit resistance, impact resistance, high and low temperature resistance, superior abrasion resistance, washing resistance and good flexibility.