The invention relates to a method for preparing a polyacrylic ester foaming regulation agent with a multi-layer nuclear shell structure. The method prepares an acrylic ester nuclear shell copolymer with a multi-layer nuclear shell structure, which uses an acrylic ester homopolymer as a nucleus and uses acrylic ester and a modified monomer copolymer as shells. The method comprises the following steps: a. pre-emulsifying a nuclear layer monomer; b. pre-emulsifying a shell layer monomer; c. preparing acrylic ester emulsion; finally obtaining multi-layer nuclear shell acrylic ester copolymer emulsion; freezing, washing, drying and the like to obtain acrylic ester copolymer powder with the multi-layer nuclear shell structure. The method greatly improves the plasticizing time and the fusant strength of rigid low-foaming polyvinyl chloride, is beneficial to the dispersing effect of particles in a polyvinyl chloride set and fully develops the function of plasticizing and improving the fusant strength.