. A Bulk RF MEMS switch is present in this paper. The beam structure and transmission line are separated fabricated on silicon and gallium arsenide (GaAs) wafer. The beam structure, up electrode, contact and anchor are fabricated on the silicon wafer. And transmission line and down electrode are made on the GaAs substrate. Two parts of the switch are bonded together by wafer bonding using gold layer as seed. The total area of the switch is 600 um X 600 um.