Abstract: A plugging material is prepared from the following raw materials in terms of mass fractions, which include: 1 to 3.6 parts of PETA-modified bisphenol A epoxy resin, 1.5 to 2.4 parts of addition product of m-phenylenediamine and methacrylic acid, 0.12 to 0.17 parts of nanosilica dispersion liquid, with the remainder being water, such that the sum of the mass fractions of the aforementioned raw materials totals 100 parts. The preparation method includes: pouring a water phase mixture into a continuously stirred oil-phase mixture to form a gel-forming liquid through continued stirring; transferring the gel-forming liquid to be mixed with dibenzoyl peroxide, and stirring and reacting at a temperature of 50° C. to 120° C. to obtain the plugging material. The plugging material is resistant to high temperatures and high salinity, and exhibits strong plugging performance.