Silk fibroin model peptide, alanine pentamer was synthesized through solid-phase method and modified with poly(ethylene glycol). Nuclear magnetic resonance spectrometry and Fourier-transform infrared spectroscopy showed the conformation of alanine pentamer, $eta$-sheet structure and random coil conformation were not changed with PEGylation. Differential scanning calorimetry showed that relatively strong exothermic peak around $180^{circ}C$ by PEGylation. No cytotoxicity of PEGylated pentamer was observed by L929 cell proliferation test.