Abstract: In this paper,a fitting of pipeline within workpieces in 2D-industrial CT image sequence is studied.First,in the important steps of acquiring the edge images,the facet model is used to extract the edge of pipeline.Next,the round and oval edges are tracked out with Freeman chain tracking method.Finally,2-D pipelines are fitted by the Least Squares and Direct Ellipse Fitting and the parameters?of pipes are calculated.Test of the actual engine CT images showed that this method can be used for the acquisition of pipelines' geometric parameters based on industrial CT images.It lays the foundation for reverse engineering based on ICT images.