Large LNG tanks are insulated by perlite.The accumulation of running time, the fluctuation of tank pressure, the vibration caused by the start-up and shutdown of equipment in the tank and the unloading process will lead to the uneven subsidence of perlite in varying degrees.If not handled in time, it will affect the cooling effect of the storage tanks and damage the storage tanks seriously. Based on the on-line filling practice of perlite in large LNG tank at Zhuhai LNG receiving station, the perlite filling replacement device, pressure control of storage tank, filling height of perlite, and practical evaluation methods are analyzed and studied.The perlite settlement representation of LNG storage tanks and the control of on-line perlite filling process are discussed.The on-line perlite filling method and experience of large LNG storage tanks are summarized, which provides reference for carrying out perlite online filling by other LNG receiving stations.