A series of crosslinked waterborne polyurethane(WPU) were prepared through a prepolymer process using isophorone diisocyanate,hexamethylene diisocyanate,dimethylol propionic acid,propylene glycoland polybutylene adipate as raw materials.The effects of NCO/OH mole ratio and trimethylolpropane(TMP) content on the properties of waterborne polyurethane films were studied.The properties of the WPU films were characterized by FT-IR,contact angle measuring instrument,thermogravimetric analysis(TGA) and X-ray diffraction(XRD).The results show that the tensile strength increases with the increase of NCO/OH mole ratio and TMP content.The water resistance and mechanical properties are greatly improved with the increase of TMP content.The XRD analysis shows that the crystallization in soft regions disappears when w(DMPA) is higher than 5.1%,and the soft segment crystallinity decreases with DMPA content increasing.