The invention discloses a metal roof rustproof waterproof repairing paste, which comprises, by weight, 65-70 parts of water, 2.0-4.0 parts of an aqueous pigment dispersing agent, 8-18 parts of ash calcium powder, 8-18 parts of titanium dioxide, 60-90 parts of zinc phosphate, 25-50 parts of aluminum tripolyphosphate, 450-600 parts of an emulsion, 250-350 parts of heavy calcium powder, 5.5-8.5 partsof anti-flashrust aid, 3.0-5.0 parts of a defoamer, 2.0-3.5 parts of an anticorrosion agent, and 4.0-6.0 parts of a rheological aid. According to the present invention, the metal roof rustproof waterproof repairing paste can form the firm protection layer using iron phosphate as the main body, and the protection layer is densely passivated and insoluble in water so as to provide good anti-rust effect; and the emulsion has advantages of good elasticity, good flexibility and good weather resistance, cannot subjected to thermal expansion and cold contraction, can resist crack, and can form the dense hydrophobic film during the drying so as to provide good waterproof effect.