Abstract: This paper introduces a case of GIS ultrasonic partial discharge (PD) signal abnormality caused by magnetostriction. The paper conducts a comprehensive analysis and assessment of the ultrasonic and ultra-high frequency PD signal characteristics and SF6 decomposition test results of the case, and at the same time locates the defects accurately. Based on this, it concludes that the cause is magnetostriction induced vibration. Finally, the paper compares and distinguishes ultrasonic and ultra high frequency PD signals caused by magnetostriction induced vibration, mechanical vibration and floating discharge, and summarizes the typical features of the magnetostriction induced vibration.