In the digital contrast measurement technology, how to ensure the accurate and reliable matching of the measured point cloud data of C-beam and the standard digital model is still a technical problem in the field of aerospace manufacturing. After a preliminary analysis of the deformation state of the C-beam after forming, it is found that the deformation is mainly the inward-facing contraction deformation of both sides, and the deformation of the bottom surface is almost negligible. In order to better compare the measured data and digital-to-analog, combined with the preliminary analysis results, this paper adopts the combination of point pair feature (PPF) coarse registration and iterative closest point （ICP） fine registration, and carries out the research on the registration technology of C-beam measured data and theoretical digital model. After rough registration, in order to improve the accuracy of fine registration, the three-dimensional point cloud structure of C-beam is divided into planes, and the bottom with small deformation is selected as the fine registration local constraint for registration. The research shows that the method can effectively improve the accuracy of C-beam digital model and measured data registration. Finally, in the subsequent measurement, the C-beam processing quality can be analyzed according to the difference between the measured data and the standard digital model. Our method has high application value for engineering practice.