Due to the increasing resistance of pathogens to antibiotics, novel antibacterial nanocomposite materials have been attracting increasing research interest. Herein, we report a facile synthetic method for a novel highly antibacterial nanocomposite based on graphene oxide (GO) nanosheets decorated with cuprous oxide by a two-step method. The as-prepared nanocomposites were comprehensively characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray (EDX) spectroscopy, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The nanocomposite was investigated for antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) using the medium dilution method and the disc diffusion method. The results showed that the synthesized Cu2O-GO has good antibacterial activities. At the nanocomposites concentration of 100 mu g/mL, the inhibition rate against E. coli reached 68%, while the inhibition rate against. S. aureus reached 32%.