The invention relates to high-cost-performance and high-stain-resistance elastic flat-coating emulsion paint. The emulsion paint is prepared from water, cellulose, a pH regulating agent, a dispersing agent, a wetting agent, a wetting anti-freezing agent, an anti-freezing agent, a defoaming agent, titanium dioxide, filler, ultraviolet crosslinking type elastic emulsion, a water-based paint enhancing agent, sterilization preservatives, a mould-preventing agent and other thickening agents except cellulose, wherein the filler is prepared from one or any combination of heavy calcium carbonate, calcined kaolin, precipitated barium sulfate, talcum powder and mica powder. The emulsion paint overcomes the defects that existing elastic flat-coating emulsion paint cannot have high stain resistance and high elasticity at the same time, and a preparation method is complicated, and has the advantages that high stain resistance (stain resistance is smaller than 15%) and high elasticity (room-temperature tensile strength is larger than 2.5 MPa, normal-temperature break elongation is larger than 300%, and low-temperature break elongation is larger than 80%) are achieved at the same time, defoaming performance is excellent, manufacturing cost is low, cost performance is high, and the preparation method is simple and convenient.