The invention discloses unsaturated polyester transparent primer for construction in high-humidity environment, comprising, by weight, 40 to 50 parts of PE (polyethylene) resin, 2 to 5 parts of 60% aldehyde ketone resin liquid, 3 to 5 parts of polishing aid, 2 to 5 parts of active solvent, 36 to 41 parts of inorganic filler, 0.4 to 0.6 part of fumed silica, 0.1 to 0.5 part of defoamer, 0.2 to 0.5 part of leveling agent, and 0.1 to 0.3 part of theological additive. The unsaturated polyester transparent primer high in performance has excellent performances in the high-humidity environment construction such as good leveling property, high fullness, good transparency, high gloss, cracking resistance and polishing easiness, the applicable range is greatly widened, and less environmental pollution is caused; by the proportioning of the unsaturated polyester resin, active solvent, inorganic filler and functional additive, the defects in the high-humidity environment construction such as poor leveling property, poor fullness, poor transparency and loss of gloss can be well overcome.