The invention relates to high-oil-adsorption resin and a preparation method thereof, and belongs to the technical field of oil-adsorption resin. The high-oil-adsorption resin comprises an oil phase and a water phase, wherein the oil phase is prepared from, by weight, 4-8 parts of divinyl benzene, 20-30 parts of styrene, 20-30 parts of n-lauryl acrylate, 20-30 parts of butyl acrylate, 20-30 parts of butadiene rubber, 3-9 parts of azodiisobutyronitrile and 40-50 parts of methylbenzene, and the water phase is prepared from, by weight, 5-9 parts of polyvinyl alcohol, 10-20 parts of gelatin, 5-8 parts of NaCl, 5-10 parts of CaCO3 and 500-600 parts of deionized water. According to the high-oil-adsorption resin and the preparation method thereof, the high-oil-adsorption resin is prepared by taking adopting a suspension polymerization technology, taking the styrene, the n-lauryl acrylate, the butyl acrylate and the butadiene rubber as the raw materials, taking the azodiisobutyronitrile as an initiator and taking the divinyl benzene as a cross-linking agent, and the adsorption quantity of the oil-adsorption resin is greatly increased.