Stable clay/waterbe polyurethane nanocompostie dispersions were synthesized by sulfonated poly ( butylene adipate ) diol , 4,4-diphenylmethane diisocyanate , dimethyl propionic acid, 1,4-butanediol, triethyl anine and clay-water dispersion through a route named prepolymer acetone mixing progress. The reinforced mechanical properties and thermal resistance of films casting from it were examined by dynamic mechanical analyses (DMA), thermogravimetric analyses (TGA) and tensile tests. Furthermore, the morphology of these nanocompostie films and dispersions were observed by transmission electron microscopy (TEM), scanning electron microscopy( SEM), wide-angle X-ray diffraction analyses( WXRD ). The experimental results reveal that the clay could be predominantly dispersed in the pristine polymer forming nanocomposties, and evidendy enhanced the tensile properties and modulus of it. Additionally, the best-reinforced effect could occur when the clay content was near 1 wt% .