Abstract: Nanocomposites of poly(hydroxybutyrate-co-hydroxyvalerate)(PHBV)and rice straw-derived nanocrystalline cellulose(NCC)modified by polyethylene glycol(PEG, 5%, 10%, 15%, 20%, 30%, weight percentage)were prepared with solvent casting method, and the interfacial bonding and crystalline properties of nanocomposites were investigated by fourier infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), and differential scanning calorimeters(DSC). The results showed that the interfacial compatibility between NCC and PHBV improved due to the formation of hydroxyl, C—O, O—C—O and C=O. With incorporation of PEG, the crystallization temperature and crystallinity of nanocomposites were both decreased. When PEG was 30%, the crystallization temperature decreased 20.4 ℃, and crystallinity of nanocomposites was reduced by 53%.