Abstract: This paper mainly explored the changes of structures and properties of silk fibers after being grafted with dodecafluroheptyl methacrylate.Modern analysis tools such as scanning electron micrograph photographs(SEM),infrared spectroscopy (IR),wide-angle X-ray diffraction patterns(WAXD),amino acid analysis etc.were used to study the structure of silk fibers after grafted with dodecafluroheptyl methacrylate.The results showed that dodecafluoroheptyl methacrylate was grafted onto silk.Furthermore,the graft copolymerization reaction took place in the amorphous region of the silk fibers such as TYR,ARG,GLU etc.,the crystal area was not destroyed during the reaction,however,the grafted silk had some damnification when the silk obtained higher graft yield.