The invention provides a quickly cured polyurethane protective paint, and a preparation method and application thereof. The polyurethane protective paint contains a polyurethane soft segment provided by polyether polyol and a polyurethane hard segment provided by isophorone diisocyanate. The mass ratio of the polyurethane hard section to the polyurethane soft section is (1: 2)-(2: 1). By accurately controlling the molecular structure of the resin, the low-temperature fast curing of the repair coating can be effectively realized. Compared with a common repairing coating, the prepared polyurethane paint is faster in curing time, high in heat stability, excellent in film coating performance, good in adhesive force, flexibility, abrasion resistance and weather resistance and capable of guaranteeing the product quality and prolonging the service life.