The organic-inorganic hybridized polymer system is studied for its photorefractive, which is sensitized by CdS nanoparticles, and combines PVK polymer to transmit carriers, DO3 nonlinear chromophores and ECZ as plasticizer. It is confirmed that the CdS colloidal particle has a nanoscale size and quantum confinement effect by adopting transmission electron microscopy and UVVisible absorption spectroscopy. The photoconductive properties of the PVK-CdS thin films is studied. Significant enhancement in photoconductivity induced by charge transform between CdS nanoparticles and PVK has also been demonstrated. An asymmetric twobeam coupling gain of 78.4 cm-1 is obtained without the external electric field, confirming the photorefractive effect of the polymer. The experimental results showed that the polymer film possesses strong photoinduced orientationenhanced photorefractive effect. When irradiated by two coherent beams, the sample can set up refractive index grating with the diffraction efficiency of 4.4%.