Elastic emulsion was prepared by means of copolymerization of siloxane monomers and acrylate monomers. The copolymerization mechanism was discussed and the influence of polymerization conditions, contents of siloxane monomers, vinyl siloxane monomers, kind and ratio of acrylates on the properties of emulsion and its film was studied. The results showed that the coat of this siloxane/acrylate copolymeric emulsion has excellent stain resistance and water proofness.