The detection and positioning of pipeline deformation is of great significance to improve the efficiency and ensure the safety of pipeline operation. In this paper, the caliper inspection is used to obtain the geometric information of pipeline deformation, and the inertial positioning technology is used to obtain the geographic and circumferential information of deformation, and finally forms a three-dimensional model of pipeline deformation, according to which the geometric characteristics of deformation are analyzed and then provides the basis for pipeline maintenance. In order to verify the effectiveness of the method, a prototype of pipeline deformation detection principle has been designed and the towing experiment has also carried out. The experimental results showed that the prototype can effectively detect and locate the convex deformation and circumferential weld of the pipeline.