Abstract: Different grain sizes of single-crystal graphene were successfully synthesized on copper foils by chemical vapor deposition（CVD） and their continuous polycrystalline graphene films were also obtained via two-step growth.The morphology and structure of as-synthesized graphene were characterized by optical microscopy and Raman spectroscopy.The Hall effect investigations for the transferred graphene films on SiO₂ substrates revealed that the grain size of single-crystal graphene had a great influence on the electrical properties of its continuous films,and it showed that larger grains could offer smaller square resistance and larger carrier mobility.