Abstract: The autoclaved aerated concrete(AAC) were manufactured by using iron ore tailings as the siliceous materials and cement and lime as calcium materials in order to find a new way to efficiently and comprehensively utilize the iron ore tailings from Nanqi mill plant，Lingqiu in Shanxi province.Factors that affect on the mechanical properties of AAC，including heating-up time，constant time，constant temperature，cooling time were studied.The results showed that AAC products with the compressive strength of 5.28 MPa and the dry density of 597 kg/m3 was achieved at conditions of 2 h heating up，8 h constant temperature at 195 ℃(constant pressure 1.46 MPa) and 3 h cooling.The mechanical properties of AAC products well fit the level A3.5，B06 qualification requirements of GB/T11968-2006.XRD analysis showed that the main hydration products of AAC were tobermorite and hydroxyl hydrated calcium silicates.Quartz，plagioclase and other minerals from the iron tailings still exist in the AAC products，and can greatly increase the strength of AAC products as aggregate.

Key words: Iron tailings, Aerated concrete, Autoclaved curing system, Compressive strength, Dry density, Hydration products, Tobermorite, Hydroxyl hydrated calcium silicates