Hyperbranched aqueous poly(urethane-urea) (HBAPU) was synthesized via A(2) + bB(2) approach using 2,4-tolylene diisocyanate, polycarbonatediol, dimethylol propionic acid and diethanol amine as materials. The structure of the products were characterized by FT-IR and C-13 NMR. The results showed that the degree of the branching increased with increasing the molar ratio of the nNCO/nOH. The particle size, thermal and mechanical properties were measured by photon correlation spectroscopy, thermal gravimetric analysis and tensile tests, respectively. The particle size of HBAPU was much smaller than that of linear aqueous polyurethane; thermal stability of HBAPU enhanced with decreasing the molar ratio of nNCO/nOH. The tensile tests revealed that HBAPU exhibited excellent tensile properties and the maximum tensile strength was up to 33 MPa.