Abstract: Graphene films were successfully synthesised on Cu foils by a home-made chemical vapor deposition（CVD） equipment,and their morphology and structure were characterized by optical microscopy and Raman spectroscopy.The influences of Cu foils surface treatment and gas flow rates on quality of graphene films were studied.The results show that the ammonia treatment can remove a variety of impurities so as to clean the Cu foils and to improve the crystal quality of graphene,optimizing the CH₄ and H₂ gas flow rate leads to flewer-layer,more homogeneous graphene films.Finally,we obtained homogeneous single-layer graphene films over 1.5cm×1.5cm area under the condition of CH₄: H₂= 200: 0 sccm on Cu foils.