Abstract: Using industrial CT to achieve high-precision measurement of internal dimensions of precision parts has gradually become an important technical means for product quality control, and CT image segmentation and data fitting are the main determinants and difficulties of industrial CT image measurement. In view of this, this paper adopts the image segmentation method of combining wavelet transform and RSF model to accurately segment the CT images of precision parts and to obtain the edge contour data of the region of interest. Hereafter, the least-squares fitting method was used to obtain the circle and line equations, and then measure the diameter and angle values of the object of interest; meanwhile, for the measurement of the wall thickness of the part, the minimum distance search method was used to obtain the wall thickness value. The measurement results of several sets of CT images of precision parts show that the measurement accuracy of WT-RSF method is generally better than that of the general measurement software VG Studio Max, and has certain engineering application value.