Simulation for cone beam CT system and the 3D Shepp-Logan Model is carried out.FDK reconstruction algorithm is developed to reconstruct the images and then evaluated with the 3D Shepp-Logan Mode.Experiments are carried out on a constructed cone beam CT system and a homemade phantom.Simulation and experimental reconstruction results indicate that reconstruction algorithm can faithfully provide both the position and relative contrast of the inner objects.The spatial resolution of the central image from simulation data can reach 8 linepairs/mm.