In a uniformly copolymerized one-part polyurethane resin composition with improved processing behaviors and chemical resistance, the one-part polyurethane resin composition comprises about 20 to 50% by weight of a hard segment and about 50 to 80% by weight of a soft segment. The hard segment reduces drying time and recoating time of a film coated by the composition, and the soft segment improves processing behaviors of the film including rolling and spraying properties. The one-part polyurethane resin composition may further comprise a catalyst. The catalyst may regulate film drying time and improve gloss of a coated film. Thus, the resin composition may be applied in various fields.