Abstract: The freeze-drying experiment of apples was studied in the paper, and obtained the freeze-drying technology for apple slice. The freezing time, drying time were calculated, and contrasted by experimental value. The influence of freezing rate, materiel temperature ,the temperature and pressure of drying room and water catching machine on the freeze drying process and the quality of the products was discussed. The optimal parameters of freeze-drying technology for apple slice are that the freeze time is 1.0h, sublimation and desorption pressure of drying room is 70～90Pa and 20～30Pa, materiel temperature in desorption is 50～60℃, material thickness is 10mm, freeze-drying time is 10h.

Key words: apple, freeze-drying, optimization of technology