In this work, bauxite cement and clay were used as raw materials to prepare anorthite insulation refractory by foaming method. On the basis of analyzing the effect of sintering temperature (1 110~1 310 ℃) on the microstructure and properties of anorthite insulation refractory by XRD, SEM and thermal conductivity meter, the synthesis mechanism of anorthite insulation was studied. The results show that when the sintering temperature is between 1 110 ℃ and 1 160 ℃, anorthite begins to form, but the reactions between raw materials are not complete, the liquid phase content is less and the strength is lower. When the sintering temperature is between 1 210 ℃ and 1 260 ℃, the liquid phase content increases, the rate of anorthite formation was accelerates, the strength increases, and the samples have a low thermal conductivity. When the sintering temperature is 1 310 ℃, the liquid phase content increases rapidly, the linear shrinkage rate increases rapidly, and the samples have higher strength, but the bulk density increases significantly and the porosity decreases. At 1 260 ℃, the anorthite insulation refractory is prepared, with bulk density of 0.53 g/cm3, porosity of 82.6%, flexural strength of 1.15 MPa, compressive strength of 1.99 MPa, and thermal conductivity of0.101 W/(m·K) at 800 ℃.