Silk fibroin (SF)/fucoidan blend films with different blend ratios were prepared by mixing aqueous solutions of SF and fucoidan.The structural characteristics and thermal properties were examined through Fourier transform infrared (FTIR) spectroscopy,X-ray diffractometry (XRD),thermogravimetry,and differential scanning calorimetry (DSC).The conformation of SF in blend films was revealed to be a β-sheet structure,according to the results of FTIR and XRD spectra.This result was also confirmed through DSC thermograms,the exotherm at around 230℃,that was attributed to the random coil conformation of SF,was not observed in blend films.These results demonstrated that the conformation change of SF occurred from a random coil to a β-sheet structure due to the formation of intermolecular hydrogen bonds between fucoidan and SF in the blend films.The crystalline SF films showed higher thermal stability than the amorphous SF film.