The invention discloses UV-curable sanding primer which is characterized by comprising the following raw materials by weight: 60 to 65 percent of bisphenol A-type epoxy resin E-42, 2 to 3 percent of benzophenone, 20 to 30 percent of TPGDA, 10 to 15 percent of n-butanol, 2 to 3 percent of modified carborundum, 1 to 2 percent of nano SiO2, 0.5 to 0.8 percent of one or more antifoaming agents, and 0.4 to 0.6 percent of one or more dispersing agents. The UV-curable sanding primer has the advantages that as the volatility and the odor are low, the environmental pollution is low; the hardness is relatively high, the sanding property is excellent, the UV-curable sanding primer is easy to sand, and the filling capability reaches a certain extent; the curing speed is fast, and the production efficiency is high; being cured at ordinary temperature, the primer is suitable for various base materials; energy is saved, that is, the energy consumption is about 1/5 of that of the conventional coating; the performance indexes, of a coating made of the primer, in all aspects, such as wear resistance, acid and alkali resistance, salt spray resistance and gasoline resistance, of an organic solvent are all very high, and particularly, a paint film made of the primer is plump and outstanding in luster.