The invention provides a corrosion-resisting and thermal-insulating waterborne metal coating and a preparation method thereof. The coating comprises raw materials in parts by weight as follows: 30-50parts of silicon-styrene emulsion, 10-20 parts of active xonotlite slurry, 6-9 parts of hollow glass beads, 3-6 parts of titanium dioxide, 0.2-0.5 parts of a dispersing agent, 0.1-0.3 parts of a wetting agent, 0.1-0.3 parts of a defoamer, 2-4 parts of a coalescing agent, 0.2-0.5 parts of a thickener, 0.1-0.3 parts of a mildew preventive, 1-3 parts of an antifreezing agent and 20-30 parts of deionized water. The invention further provides the preparation method of the coating. The corrosion-resisting and thermal-insulating waterborne metal coating not only has good low-temperature stability andresistance to water, acid, alkali and neutral salt mist, but also has the advantages of good coating temperature alternating resistance, reflectivity, thermal insulation, decorative performance, corrosion resistance and the like.