Objective: To optimize selection of collagen sponge freeze-drying process

such as collagen protein molecules of freeze-drying reference. Method: Orthogonal test was used to choose the best collagen sponge freeze-drying process with water imbibition and re-hydration values as index. Result: The rate of pre-freezing was 0.35 ℃ ·min-1

the duration of pre-freezing was 1.5 h

the lowest temperature of pre-freezing was -35 ℃ and the temperature of the first sublimation was -10 ℃. Conclusion: The pigskin collagen sponge produced by the freeze-drying process which has been chosen is osteoporosis and porous

the water imbibition and re-hydration of the pigskin collagen sponge are well.