The authors developed nondestructive testing equipment to automatically and efficiently determine log defects for better wood utilization. It is based on computed tomography(CT) technology which can reconstruct a two-dimensional image and a three-section image of wood by scanning wood cross sections. The images provided by the equipment clearly and accurately show the positions of annual rings, knots and cracks in the wood. Based on these CT scans, these internal structural features can be used for nondestructive testing and for timber classification.