The invention relates to a resin microsphere plugging agent and a preparation method therefor. The resin microsphere plugging agent is prepared from the following ingredients in parts by mass: 30-60 parts of alkene monomer, 5-40 parts of ester monomer, 5-10 parts of functional monomer, 0.1-1 part of organic dispersant, 0.3-0.5 part of inorganic dispersant, 0.6-1 part of oil-soluble initiator and 80-120 parts of distilled water. The resin microsphere plugging agent is obtained through adding the organic dispersant and the inorganic dispersant into deionized water, carrying out heating, stirringand mixing, adding the oil-soluble initiator into a mixture of the alkene monomer, the ester monomer and the functional monomer, dissolving the oil-soluble initiator, mixing all the ingredients, carrying out a polymerization reaction so as to obtain a dispersion solution of different particle sizes, and carrying out stirring to cool the dispersion solution to room temperature. According to the resin microsphere plugging agent and the preparation method therefor, the technological operations are simple, and prepared resin microspheres have the advantages of uniform particle size, easy-controlled reaction temperature, high yield, good stability, good flexibility, good transparency, good heat resistance and difficulty in degradation.