Silk fibroin solution was prepared by dissolving the silk fibroin in triad solvent CaC2 . CH3CH2OH . H2O. In this article we tested and analyzed the state of frozen silk fibroin solution and fine structure of freeze dried porous silk fibroin materials. The results indicated that the glass transition temperature of frozen silk fibroin solution ranges from -34 to -20 degreesC, and the initial melting temperature of ice in frozen solution is about -8.5 degreesC. When porous silk fibroin materials are prepared by means of freeze drying, if freezing temperature is below -20 degreesC, the structure of silk fibroin is mainly amorphous with a little silk II crystal structure, and if freezing temperature is above -20 degreesC, quite a lot of silk I crystal structure forms.