A high-solid content pure acrylate elastic emulsion used for preparing coatings for the outer walls of buildings is prepared by adopting a core-shell emulsion polymerization method. The formula of theelastic emulsion consist of the following components: 4-13% of methyl methacrylate, 7-24% of butyl acrylate, 7.5-15% of acrylonitrile, 1-5% of allyl methacrylate, 6-17% of shell monomer: methyl methacrylate, 12-24% of butyl acrylate, 7.5-15% of acrylonitrile, 1-3% of methacrylic acid, 1-5% of emulsifier, 1-3% of persulfate and 35% of water. Compared with the prior art, the prepared coatings for the outer walls have the advantages of strong water resistance and contamination resistance, good elasticity, less cracked shape of coating films, saved painting manpower and the like.