The invention relates to a water-based colorful architectural coating and a preparation method thereof, belongs to building materials, can enable an external wall to obtain a marble visual effect through painting the water-based colorful architectural coating, and overcomes the defects that through the conventional coating, the marble visual surface cannot be obtained, and during dry hanging of a marble slab, the cost is high, and the safety is poor. The water-based colorful architectural coating comprises protecting rubber powder, latex, titanium white pulp, water, a plural gel, kaolin, a film-forming additive, a thickening agent and proper quantities of high-grade water dispersible pigments, wherein the plural gel comprises a suspending agent, a sizing agent and a gel according to corresponding proportion. The preparation method comprises the following steps: preparing protecting rubber solution, preparing a base coating, preparing a continuous phase, and pelleting to obtain the water-based colorful architectural coating. The water-based colorful architectural coating and the preparation method have the positive effects that the water-based colorful architectural coating is suitable for wall outer layer decorative surfaces, has high simulation, can not only simulate granite, but also embody the decorative effects of natural marbling and lines through adjusting the content of the protecting rubber solution and kaolin, and meanwhile has the advantages of low cost, environmental protection, energy conservation, superstrong self-cleaning function, cracking resistance, short construction period and long service life.