A spraying fast-setting rubber asphalt waterproof material special for exterior wall and a preparation method thereof belong to the field of waterproof coatings. Said waterproof material comprises a component A and a component B. The component B is a coagulant solution formulated by adding water to calcium chloride, sodium chloride and a composite aluminum-iron polymer. The component A comprises 30 to 50 parts of a polymer latex, 50 to 70 parts of an emulsified asphalt, 5 to 30 parts of a reinforcing aid, and 0.3 to 1.5 parts of other aid. The reinforcing aid is a nano silica sol. The other aid is one or more of an antioxidant, a light stabilizer, a mildew preventive and a defoamer. The polymer latex is selected from latexes having a high gel content, and a nano silica sol is added into the component A. After film formation, the tensile strength is ≥ 1.2 MPa, the elongation is ≥ 1000%, and the bonding strength is ≥ 0.8 Mpa. The waterproofing material has good high and low-temperature performance, is resistant to acids, alkali and salts, has good weather resistant performance, and still has good waterproof property even if the plaster layer and the decorative layer are cracked.