The invention discloses UV photocuring topcoat. The UV photocuring topcoat is prepared from, by weight, 20-25% of cycloaliphatic epoxy resin CER-170, 8-12% of aliphatic urethane acrylate DH-318, 30-35% of HDDA, 5-10% of benzil dimethyl ketal, 10-20% of isopropanol, 10-15% of modified mica powder, 5-10% of talcum powder, 1-2% of dispersing agents and 0.5-0.8% of antifoaming agents. The UV photocuring topcoat is low in volatility, low in smell, low in environmental pollution, high in hardness, good in hand feeling and glossiness, high in curing speed, high in production efficiency, capable of being cured at the normal temperature and applicable to a variety of substrates; by means of the UV photocuring topcoat, energy is saved, and energy consumption accounts for 1 / 5 that of a traditional coating; performance indexes of all aspects such as coating transparency, acid and alkali resistance, salt spray resistance and resistance to organic solvent such as gasoline are high, a paint film of the topcoat is particularly plumpy, and gloss of the topcoat is particularly outstanding.