Large-size, high-density workpieces used in industrial computed tomography (CT) scanning can cause problems such as incomplete projection data and terrible artifacts in reconstructed images owing to a lack of penetration and limited scanning angles. To address such limitations, this study uses a CAD model of the workpieces as prior knowledge and realizes superior reconstruction of the limited CT angle occurring in these types of objects. The layered position corresponding to the CAD model is calculated by the tomography workpiece position of the CT scan, and the pixel section of the model is obtained. Then, an attenuation coefficient image is obtained and generated according to the X-ray energy of the CT system and material of each part of the model that is registered into a zero gray image to obtain a prior image. Finally, the simultaneous algebraic reconstruction technique+total variation minimization+prior image (SART+TVM+PRIOR) algorithm is used to iterate the scanned projection data to obtain the reconstructed image. The experimental results of the simulation and actual workpiece scanning indicate that the quality of reconstructed image with the prior image is significantly improved over that without the prior image. This improvement is reflected mainly by a substantial reduction in artifacts in the clearer edge structure.