An optic-based X-ray tomography system of a high spatial resolution using a conventional X-ray tube was proposed. The system had several X-ray optics: multilayer mirror for monochromatic X-ray, capillary optic for focusing X-ray onto a sample, and objective zone plate. The X-ray tomography system was designed for obtaining a spatial resolution of 100 nm. Design parameters for each optic were determined and optimized by ray tracing in considering X-ray intensity and reflectivity. The X-ray tomography system with a spatial resolution of 100 nm will provide a good inspect tool in bio-medical field and semiconductor applications. Crown Copyright (C) 2011 Published by Elsevier B. V. All rights reserved.