The　twin-roller　casting　process　is　a　novel　technology　used　to　produce　aluminium　and　other　alloys.　In　this　study,　the　Al-Fe-Si　alloy　was　twin-roller　cast　into　a　billet　with　a　thickness　of　7.0　mm.　This　was　followed　by　an　annealing　process　at　480　degrees　C　for　16　hours.　Abnormal　grains　of　more　than　15　mm　in　the　nominal　diameter　were　found　to　have　formed　on　the　surface　of　the　billet.　Scanning　electronic　microscopy　observation,　energy　diffraction　spectrum,　microarea　X-ray　diffraction,　and　electronic　backscattered　diffraction　analysis　were　performed　to　study　this　abnormal　grain　growth.　The　results　showed　that　abnormal　grain　nucleates　in　the　region　of　(100)　texture　formed　in　the　twin-roller　casting　process.　The　growth　of　abnormal　grain　was　governed　by　the　coalescence　of　the　abnormal　grain　with　its　surrounding　normal　grains,　with　an　average　orientation　angle　of　47　degrees　between　both　the　types　of　grains.　High-strain-concentrated　regions　on　the　surface　layer　of　the　billet　were　induced　by　the　heterogeneously　distributed　Fe　particles　formed　in　the　twin-roller　casting　process.　The　presence　of　these　regions　accelerates　the　abnormal　grain　growth　in　the　following　annealing　process　of　the　billet.