The invention discloses a low-viscosity hydroxyl-terminated resin with diisocyanate as a core, and a preparation method therefor and the use thereof. During preparation, 1 mole of a micromolecular polyol is first modified with 1-3 moles of a monoepoxide so as to obtain a modified polyol; and then 2 moles of the modified polyol is reacted with 1-3 moles of a diisocyanate so as to obtain the hydroxyl-terminated resin. The prepared hydroxyl-terminated resin has the advantages of simple synthesis process, high solid content and low viscosity; the hydroxyl value thereof (at 80% solid mass content) is 140-300 mg KOH/g and the viscosity thereof at 25° C. (at 80% solid mass content) is 300-3000 cp. The hydroxyl-terminated resin is capable of crosslinking with a polyurethane curing agent containing isocyanate groups, and the prepared high solid content dual-component polyurethane coating has a VOC content of less than 380 g/L at the applicable viscosity thereof, and the performance of the coating meets the national standards for solvent based dual-component polyurethane woodenware coatings.