Abstract: The thick SOI films were prepared by SIMOX technology and Si epitaxy process.The thick SOI materials were characterized by Secco etching,SE and SRP.The dislocations and stacking faultsin epitaxial Si layer mainly result from the dislocationsin the SIMOX SOI substrate and the roughness of the substratesurface.The quality of SOI substrate affects epitaxial Si layer greatly.The resistivity of epitaxial layer is uniform.The rib waveguide was fabricated on the thick SOI material.Light can transmit in the waveguide successfully and the loss is 0.4dB/cm.