When the two-dimensional CT image and the design model are used to analyze the manufacturing error, it requires the position of CT image in the design model. To determine the position, it needs to find a reference position matching the design model on the workpiece. Then, the machining the position needs to be manufactured, which increases the processing cycle and manufacturing cost of the workpiece. To address this issue, this study proposes an automatic search CT image design model to complete the workpiece manufacturing error detection method. Firstly, the edge of CT image is extracted. Secondly, the point cloud design model is sliced layer by layer. Then, through Hu moment matching, ICP registration automatically searches the point cloud slices that match the CT image. Finally, according to the registration results, the error distribution of the workpiece is calculated, and the manufacturing error detection of the workpiece is completed. To evaluate the feasibility of this method, the standard workpiece with known size is used for detection. Experimental results show that the detection error is concentrated between 0~ 0. 25 pixel, which has high detection accuracy. Two actual workpieces are tested to evaluate the applicability of the method. In this study, without the need to determine the benchmark position of the workpiece, the two-dimensional CT image and design model of the workpiece are used to realize the calculation, analysis and display of the manufacturing error of the workpiece, which has high practical significance.