The invention provides a UV-curing adhesive with low Tg point and high permeability and a preparation method thereof. The UV-curing adhesive is prepared from the following raw materials in parts by weight: 10-30 parts of a self-prepared urethane acrylate prepolymer with low Tg point, 30-60 parts of aliphatic polyurethane acrylate with low Tg point, 20-50 parts of a reactive diluent with low Tg point, 0.5-5 parts of a leveling wetting agent, 2-4 parts of a photoinitiator and 1-3 parts of a silane coupling agent; the self-prepared urethane acrylate prepolymer comprises long-chain glycol, diisocyanate, a catalyst, a polymerization inhibitor, an antioxygen and hydroxyl acrylate resin; the molar ratio of long-chain glycol, diisocyanate and acroleic hydroxyl ester is 1:(1.82.0):(1.8-2.0); the catalyst, the polymerization inhibitor and the antioxygen respectively account for 0.01-0.1wt% of the urethane acrylate prepolymer with low Tg point. Compared with the prior art, the UV-curing adhesive has the vitrification temperature less than or equal to 50 DEG C, and has the performances of low surface tension is low, good wettability, good surface dryness, excellent tenacity, excellent dampness and humidity resistance, high temperature resistance and the like.