The high temperature dielectrics of Quartz fiber-reinforced silicon dioxide ceramic (SiO2/SiO2 ) composites were studied both theoretically and experimentally. A multi-scale theoretical model was developed based on the theory of dielectrics. It was realized to predict dielectric properties at higher temperature ( ＞ 1200 ℃) by experimental data mining for correlative coefficients in model. The results show that the dielectrics of SiO2/SiO2,which were calculated with the theoretical model, were in agreement with experimental measured value.