The effects of different pretreatment methods (including blanching, color protecting liquid and ultrasonic) on the quality of vacuum freeze-dried apple slices were analyzed. The results showed that the FD apple slice in the blanching pretreatment group presented obvious collapse and shrinkage in the cell wall morphology, and obtained the lowest content of vitamin C, the highest rehydration ratio 4.97 and the highest content of soluble solids after rehydration(P＜005). In the color protection pretreatment group, FD apple slices obtained firmer network skeleton with full and complete shape of the cell walls, the highest hardness value 7.17 N, the highest color difference index ΔE, brighter and whiter appearance(P＜0.05). In the ultrasonic pretreatment group, FD apple slices obtained thinner, looser and more porous network organization of cell walls, the shortest FD time 10 hours, the highest content of vitamin C and the lowest content of soluble solids after rehydration(P＜0.05).