The present invention relates to an emulsion type modifier for improving properties of the pressure-sensitive emulsion acrylic adhesives. The emulsion type modifier comprises: (a) 15 to 35 parts per hundred of monomers of a diester of a dicarboxylic acid; (b) 15 to 35 parts per hundred of monomers of vinyl esters; (c) 35 to 65 parts per hundred of monomers of alkyl acrylates; based on the total weight of (a)+(b)+(c), and (d) 0.1 to 2.0 parts per hundred of an acetoacetoxy functional monomer; (e) 0.1 to 2.0 parts per hundred of a nonionic surfactant; and (f) 0.4 to 3.0 parts per hundred of an anionic surfactant. By adding the emulsion type modifier of the present invention, the steel adhesion, polyethylene (PE) adhesion, the loop tack and the holding power of the pressure-sensitive emulsion acrylic adhesives can be improved.