Abstract: To solve the problems of the low strength of silica aerogel and the high thermal conductivity of xonotlite, silica sol was prepared with TEOS through sol-gel process, and then xonotlite-silica aerogel nanoporous super insulation materials dried by supercritical drying technique were prepared with silica sol compounded into xonotlite. A transient hot-apparatus was used to measure the thermal conductivity of samples at normal temperature in an environmental pressure range of 1.01×10⁵~1×10^-2 Pa, and the effect of preparation condition on the thermal conductivity of the composite materials was studied. It is indicated that the thermal conductivity of the composite materials decrease with decreasing unit weight of xonotlite and increasing composite mass growth rate, but they experience the changeable process from decrease to increase with increasing unit weight of silica aerogel.