The equivalent thermal resistance model of sepiolite mineral nanofibers has been presented in this paper to predict the thermal insulation properties of ﬁbrous mineral fine powders. The model was based on the correlation between thermal conduction and gas & solid conduction in the ﬁbrous system. According to the analysis about the process of heat transfer in sepiolite nanofibers, the total thermal conduction can be described as the synergism of the solid thermal conduction and the gaseous thermal conduction. From the equivalent thermal resistance model of fibrous materials in the accumulative condition, it can be seen that the thermal conduction of ﬁbrous mineral fine powders can be evaluated by the relationship between bulk density and thermal conduction of sepiolite nanofibers. Comparing the theoretical values with experimental data obtained from thermal conduction instrument, it was found that the theoretical values corresponded well with experimental data.