Abstract: Ultra-high barrier film,which can protect the organic electronic device from water vapor erosion and prolong its lifetime,is widely used in flexible OLED panels,quantum dot display and flexible photovoltaic.Atomic layer deposition(ALD)is an ideal preparation method for ultra-high barrier film on the atomic scale,affording the film with good uniformity,high purity,and precisely controlled thickness.In this paper,the basic principle,technical characteristics,and deposition conditions of ALD are reviewed.The research progresses of singlelayer and multi-layer inorganic barrier films,as well as organic/inorganic laminated barrier films prepared by ALD technology are emphasized.In addition,it is indicated that the organic/inorganic laminated structure is considered an effective method to achieve ultra-low water vapor transmittance rate(WVTR)of barrier film.Finally,the future development trend of the preparation of flexible ultra-high barrier films by ALD is prospected.