Graphene has attracted great attention in nanoelectronics, semiconductor, because of its special structure and performance, however, since its bandgap is zero, its application is limited seriously. The multi-layer graphene is prepared by chemical vapor deposition (CVD), and then doped by Br2 is to investigate and analyze the Br2 effect on graphene bandgap. In order to compare how the Br2 effect on graphene bandgap, the Raman is measured with 633 nm He-Ne laser before and after doped, the relation between graphene bandgap shift and Br2 volume is calculated according to Raman results, the results show that: Br2 doping has influence on G band, and the G band is energy up-shifted with Br2 volume before reaching a stable value; the G/2D intensity ratio also increase with Br2 volume before reaching a stable value. The measured Raman peak position blue-shifts linearly with Fermi energy, the graphene Fermi energy is calculated according to the relation between G band peak position and Fermi energy before analyzing how the Br2 effect on graphene bandgap.