A new type of layered zirconium glycine-N,N-dimethylphosphonate (ZGDMP), with the functional groups -COOH, has been prepared and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). Situ polymerization method was employed to prepare castor oil-based polyurethane/layered zirconium phosphonate (PU/ZGDMP-n) nanocomposite films. The structure and morphology of ZGDMP in PU matrix have been characterized by XRD, SEM, TEM, and Fourier transform infrared spectroscopy. The results show that the morphology and properties of PU-based nanocomposites greatly depend on the functional groups -COOH because of the chemical reactions and physical interactions involved. The tensile test shows that the tensile strength and elongation at break for the nanocomposite films increase with the loading of ZGDMP as compared to those of the virgin PU.