Aiming at the high-precision measurement requirements of the state of biological attachments in large pipelines,a contour reconstruction method using homogeneous transformation was proposed.Through coordinate transformation,the coordinates of the offset contour were corrected back to the coordinates of the accurate contour,and the contour measurement error caused by the motion position deviation was eliminated.Through the establishment of pipeline ultrasonic measurement experimental device for experimental verification,the absolute error generated after offset reconstruction is 9 mm and the relative error is 2.36%,the absolute error generated after deflection reconstruction is 6 mm and the relative error is 1.6%.The error falls within the cm-level resolution of the ultrasonic detection system,and the contour detection accuracy can be improved by improving the resolution of the ultrasonic detection system.This method can be applied to underwater pipeline contour detection and underwater robot contour-based automatic centering detection.