The invention discloses a DCPD modified self-drying type industrial alkyd resin and a preparation method thereof. The DCPD modified self-drying type industrial alkyd resin comprises semi-finished product raw materials, finished product raw materials and a solvent, wherein the semi-finished product raw materials comprise, by weight, 71-74 parts of DCPD, 14-19 parts of maleic anhydride, and 7-10 parts of deionized water, the finished product raw materials comprise, by weight, 49-51 parts of Soybean oil fatty acid, 20-22 parts of pentaerythritol, 19-21 parts of phthalic anhydride, 0.5-3 parts of benzoic acid, 0.5-3 parts of ethylene glycol, 0.1-0.3 part of an antioxidant, and 4-7 parts of the semi-finished product raw materials, the solvent is a diluted solvent according to a solid accounting for 60%, and the diluted solvent comprises toluene and 2# solvent gasoline according to a ratio of 1:4. According to the present invention, by introducing DCPD, the double bond density of the self-drying alkyd resin is increased, and the cross-linking density of the late-stage paint film is increased, such that the prepared paint film has advantages of good hardness, good scratch resistance, good abrasion resistance and good dryness compared to the conventional alkyd resin.