Boronmullite ceramics in Al-B-O system such as Al ₅BO ₉and Al ₄B ₂O ₉ have superior properties,including low density,low thermal conductivity and wide band gap.They are promisingthe in applications including thermal protection,wave transparent and thermal sealing in hypersonic vehicles.In this paper, recent progress on structure,synthesis and properties of compounds in Al-B-O system were reviewed.Theoretically,first-principles calculation based on density functional theory(DFT) is introduced to predict the crystal structure,elastic and thermal properties of these materials.Experimentally,synthesis methods such as solid-phase reaction,high-temperature molten-salt method,sol-gel method and thermal decomposition method are summarized.The applications and perspective of these materials are also discussed.