The invention discloses an aqueous high weather-proof matt exterior wall emulsion paint and a preparation method thereof. The emulsion paint comprises the following components by weight: 30-40 parts of emulsion, 0.2-0.5 part of an organosilicone hydrophobic agent, 2-8 parts of diatomite, 4-7 parts of sericite powder, 20-25 parts of titanium dioxide, 6-14 parts of a calcium carbonate powder, 0.4-0.7 part of a dispersant, 0.1-0.3 part of a wetting agent, 0.3-0.6 part of a defoaming agent, 0.1-0.3 part of an antifreeze, 1.5-2 parts of a coalescing agent, 0.4-0.9 part of a thickening agent, 0.2-0.5 part of a leveling agent, 0.1-0.3 part of a preservative, 0.1-0.3 part of a mildew preventive and 20-30 parts of water. The preparation method provided by the present invention comprises steps of: pre-blending, grinding disperse, and addition of emulsion and auxiliary agent, etc. The aqueous high weather-proof matt exterior wall emulsion paint provided by the invention has advantages of soft texture, flattening and fine paint film surface, and soft matt effect.