An ancient folk technology of freeze-thaw processing had been simulated by studying the dehydration efficiency of potatoes using different freezing rates (0.02, 0.06, 0.08, 0.11, 0.20 and 0.40 °C/min). The results showed that the dehydration rate was negatively correlated to freezing rates at a range of 35.66% to 53.85%. Better dehydration efficiency (41.71%) with relatively more protein (83.66%) and mineral retention was obtained at the medium freezing rate of 0.11 °C/min. On this condition, the internal and external pressures of potato cells were balanced and the reduction of immobilized water (T22) was significantly higher compared to that at other conditions. The untargeted metabolomic results showed that some lipids, organic acids and amino acids in potatoes were affected by freezing treatment. The dynamic changes of potato characteristics during freeze-thaw processing gained in this research could be employed as a foundation for diversified applications of dehydrated potatoes.