Abstract: GIS/GIL would inevitably produce a variety of metal particles during installation and transportation, and lamellar particles are difficult to be detected due to their "latency", which greatly threatens the insulation performance of GIS/GIL. This study used numerical calculation and experimental methods to research the lift-off and movement law of lamellar particles under power frequency voltage. The lamellar particles were equivalent using a spheroid model, and the charge amount and the critical take-off electric field strength of the lamellar particles were derived theoretically. An platform observing the movement of the lamellar particles under power frequency voltage was built. A high-speed camera was employed to observe the lift-off and movement process of lamellar particles, which were further analyzed and compared with the numerical calculation results. The results show that the lift-off electric field strength of lamellar particles is approximately proportional to one-half of the thickness, and shows a slight upward trend as the particle radius increases. After the stainless lamellar particles are upped, there are two patterns of particle movements: rotating on the spot or rolling back and forth along the surface of the ground electrode. Simultaneously, there is a weak partial discharge between the bottom of the particle and the ground electrode. After the aluminum lamellar particles are upped, they jump up and down violently and frequently in the electrode gap.