Bacterial cellulose-poly (ethylene glycol) composites (BC-PEG) were biosynthesized by adding different molecular weight of poly (ethylene glycol) into Acetobacter xylimum culture medium. The obtained BC-PEG composites were characterized by scanning electron microscopy (SEM), thermogravimetry (TG), X-ray diffractometry (XRD) and tensile test. SEM images showed that the morphology of BC-PEG composites changed. TG results indicated their thermal stability also changed. XRD profiles suggested their crystalline morphology no much difference. But the tensile tests appeared that the adding of different molecular weight PEG modified the mechanical properties of BC-PEG composites.