Gas insulated lines (GIL) are renowned for their compact design, high insulation strength, and environmental sustainability, making them a highly reliable and cost-effective choice for power systems. Ensuring the safe operation of gas-insulated lines is crucial for maintaining the reliability of the power grid. This paper proposes a method for abnormal vibration sensing of gas-insulated lines based on an optical fiber interferometer. Utilizing the high-frequency carrier method, the interference of field noise in acoustic vibration signal detection is reduced, and phase information is demodulated using the differential cross-correlation algorithm. In the field application, the abnormal sound and vibration signal is detected, which is finally confirmed to be the metal collision and impact sound caused by the stress release of the head bolt caused by thermal expansion and shrinkage, which verifies the effectiveness of the proposed method.