Abstract: In this paper, the ultrasonic time of flight diffraction (TOFD) detection simulation analysis of corrosion defects on the inner wall of a long-distance pipeline is carried out. The sound field and defect response simulation analysis are carried out by using the standard recommended weld detection process parameters, and the preliminary detection process is obtained. The detection process is tested in the actual project, and the results are compared with the conventional ultrasonic detection results. As shown by the verification experiment, the TOFD test results are basically consistent with the conventional ultrasonic test results, and the test results are intuitive, which provides an effective detection technology for long-distance pipeline inner wall corrosion defect detection.