The invention discloses a multifunctional exterior wall coating with strong weather resistance, brushing resistance and high adhesion and a preparation method thereof. The exterior wall coating is prepared from the following raw materials in percentage by weight: 10-30% of silicone acrylic emulsion with a interpenetrating network structure, 10-40% of acrylic ester emulsion, 1-15% of hydrophobically modified inorganic nanoparticles, 10-40% of pigment and filler, 0.3-1% of a dispersing agent, 0.1-0.2% of a defoaming agent, 0.1-0.3% of a preservative, 0.3-0.6% of a flatting agent, 1-2% of a thickening agent, and the balance deionized water. The exterior wall coating of the invention has the advantages of strong weather resistance, brushing resistance, strong adhesion, long service life, simple and convenient preparation process and low equipment requirement, thus being easy for large-scale popularization and application. The exterior wall coating overcomes the defects of poor brushing resistance, poor ageing resistance and the like of the existing exterior wall coating.