A series of waterborne polyurethane ( WBPU)/clay nanocomposite dispersions containing different amounts of 2,2-dimethylol propionic acid ( DMPA) and clay were prepared. It was found that the properties of WBPU/clay nanocomposites were highly dependent on both clay content and DMPA content. TheWBPU/clay nanocomposite dispersion with a higher clay content showed a larger mean particle size and a less negative zeta potential. The optimum clay content, which increased with increasing DMPA content, showed maximum tensile strength, Young's modulus and adhesive strength of WBPU/clay nanocomposite. The optimum clay concentrations for WBPU/clay nanocomposite samples containing 3.75, 5.41 and 6.17 wt% DMPA were about 0.5, 1.0 and 2.0 wt%, respectively.