The composite thin films of PT nanometer particles and high transparent polymer PEK-C were prepared. The poling conditions that PT particles in composites are aligned under external electric field was optimized through the dielectric properties of PT and PEK-C polymer and effective field intensity theory. Through the X-ray diffraction of poled composite thin film, it was obtained that the c axis orientation ratio eta of nano-crystal PbTiO3 was calculated to be 68%. The transparency spectra in the range 380-900 nm was measured. The optical band-gaps of poled and unpoled composite thin films were estimated to be 3.14 and 3.06 eV, respectively.