The invention relates to the field of fracturing yield-increase measures and oil extraction technology in the oilfield exploitation process, especially to oil-soluble resin for oil exploitation and a preparation method and application thereof. Raw materials for the preparation comprise, by weight, 45-50 parts of styrene, 10-12 parts of methyl methacrylate, 35-45 parts of dicyclopentadiene, 1-3 parts of a dispersant and 0.4-0.5 part of an initiator. The preparation method comprises the following steps: heating deionized water to 60 DEG C, adding the dispersant while stirring, adding styrene, methyl methacrylate, dicyclopentadiene and the initiator, continuously stirring and sealing and vacuumizing to -0.08 to -0.09 MPa, adding nitrogen and lifting pressure to 0.8-0.9 MPa, heating to 95-105 DEG C, controlling reaction temperature difference to +/-0.5 DEG C and reacting for 14-15 h, cooling, releasing pressure, filtering, and drying to obtain powdery oil-soluble resin for oil exploitation. The oil-soluble resin for oil exploitation can bear 15 MPa of pressure within the range of 60-120 DEG C within 4 h, and then is gradually softened and dissolved thoroughly without residues.