Acrylic acid modified water soluble polyurethane (PUA) was prepared on the basis of polyethylene glycol, 2,2-dimethylol propionic acid (DMPA), 2,4-diisocyanatotoluene (TDI) and acrylic acid as materials. Characterization and testing of the products and the influences of acrylic acid on the performance of PU were discussed. The results of Fourier-transform infrared spectroscopy demonstrate that acrylic acid is chemically tethered onto the molecular chains of PU. The PUA has better heat resistance property compared with PU by thermogravimetric analysis. With the increasing of the acrylic acid content, elongation at break of PUA decreases, and tensile strength and water absorption increase obviously.