A mathematical model of double sublimation fronts was developed for microwave freeze-drying for a cylindrical porous media with cylindrical dielectric cores.The set of transient governing equations describing the drying process were solved numerically with the variable time-step finite volume method.The numerical results showed that two sublimation fronts did exist within the porous media.Proper usage of cylindrical dielectric cores could dramatically reduce the drying time.The impact of cylindrical dielectric cores on drying could not be ignored even though the initial saturation was low(S0=0.2).