In this paper three kind of water borne polyurethane are synthesized. FTIR identify the structure of 2-hydroxypropyl acrylate terminated water borne polyurethane with block PDMS. It is found that Si-WPUA has excellent water-resistance, good toughness, and good tensile strength. So, the work has been found the method which could improve water resistance and not decrease mechanical properties. It is hoped that the modified polyurethane could be used as coatings superior to the solvent-borne systems.