The blend film of silk fibroin (SF) and poly(ethylene glycol)400 (PEG400) with a blend ratio of 2/1 (wt/wt) was prepared simply by dropping a little PEG400 into the SF solution and then casting the mixed aqueous solution at 50℃. The resulting film exhibited much better mechanical properties in the dry and wet state than SF itself, owing to the conformational change of SF in the blends from the random coil to the β-sheet structure and intermolecular hydrogen bond formation between SF and PEG400. Thermogravimetric analysis showed that the initial thermal decomposition temperature of the blend film was 170C, which was 80℃ lower than that of SF (250℃) and 20℃ higher than that of PEG400 (150℃),and indicated a strong interaction between two components of the blend. No crystalline peaks were observed in the X-ray diffraction curve of the blend film. Cell culture test showed that SF/PEG400 was a suitable substrate for the growth of human umbilical vein endothelial cells (HUVEC).