In this paper, a non-contact vibration detection method for gas insulated line (GIL) based on laser Doppler vi-brometer (LDV) technology is proposed. First, vibration frequency and amplitude distribution under normal and defect conditions are obtained by transient electromagnetic-structural coupled field finite element modeling and physical experiments. Besides measuring points on GIL surface and parameters of LDV system are also con-firmed. The 1550 nm fiber optical path component including narrow linewidth laser, optical transceiver, acous-to-optic modulator (AOM) and balanced detector is designed, and the optical beat signal which contains object movement information is successfully obtained. Vibration signal demodulation scheme based on digital orthog-onal and differential cross multiplication algorithm is developed. The mechanical vibration signals within frequency range 50 Hz?20 kHz between 0.5?20 m distance are acquired by proposed system. The developed system has been successfully applied to GIL prototype platform testing and on-site GIL inspections, effectively overcoming the shortcomings of contact-based accelerometers, such as installation difficulties, low detection efficiency, and poor accuracy. This has enabled non-contact vibration measurement for long-distance GIL equipment.