Abstract:The lightweight thermal insulation material was prepared with red mud, fly ash and silica sand as the main raw material, by the technology of mixing with physical foam, casting, calcination and so on. The influence of calcined temperature and heating rate on performances of sample was studied, the morphology was observed by scanning electron microscopy(SEM), and the sintering mechanism was explored. The results show that the optimum calcined temperature is 1150℃, the optimum heating rate is 6℃/min. Under the optimum condition, the bulk density is 527kg/m3, the shrinkage is 57%, the compressive strength and flexural strength are 34MPa and 22MPa, the thermal conductivity coefficient is 0105W/(m·K), the porosity is 3361%(by volume).