Abstract: A method for manufacturing a P.U. product includes a front stage working, and a rear stage working. The front stage working includes: coating a first P.U. liquid on a releasing sheet to form a first P.U. surface layer, coating a second P.U. liquid on the first P.U. surface layer to form a second P.U. surface layer, bonding a substrate cloth on the second P.U. surface layer, thereby forming a first product which includes the first P.U. surface layer, the second P.U. surface layer, and the substrate cloth. The rear stage working includes: rolling a first mixing liquid on the first product to form a plurality of intensive small air vents in the second P.U. surface layer for increasing permeability, rolling a second mixing liquid containing a fluoride on the first product so that the fluoride infiltrates through the first and second P.U. surface layer for increasing a water repellent function, and rolling a third mixing liquid containing a P.U.