Objective In order to understand the sublimation drying effect and sublimation drying time of potatoes optimize the freeze-drying process and reduce energy consumption during freeze-drying the COMSOL Multiphysics software was used to simulate potato slices. Methods By integrating knowledge of heat transfer mass transfer and related disciplines a physical model and a mathematical model of potato slices during the sublimation drying process were established to simulate the sublimation drying process of potato slices. Results The ratio of ice mass to initial ice mass gradually decreased as the drying time increased and the dehydration rate gradually decreased as the drying time increased. Considering that the simulation neglected the actual situation of steam flowing out from around the slices the actual value of the ratio of ice mass to initial ice mass was lower than the simulated value and the actual dehydration rate was higher than the simulated value. In fact sublimation drying could remove over 85% or even over 90% of the moisture from potato slices resulting in a good drying effect. As the thickness of potato slices increased the sublimation drying time of potato slices gradually increased. The higher the temperature in the freeze-drying chamber during potato sublimation drying the less time was needed for sublimation drying to be completed. The greater the pressure in the freeze-drying chamber the longer the sublimation drying time of potatoes. The higher the temperature of the partition the shorter the sublimation drying time of potatoes. Conclusion When freeze-drying potatoes it is advisable to increase the temperature of the freeze-drying chamber reduce the pressure in the freeze-drying chamber increase the temperature of the partition and decrease the thickness of the potatoes to reduce the energy consumption during the freeze-drying process.