This paper proposes a novel high-capacitance-ratio radio frequency micro-electromechanical systems (RF MEMS) switch. The proposed RF MEMS mainly consists of serpentine flexure MEMS metallic beam, comprised of coplanar waveguide (CPW) transmission line, dielectric and metal-insulator-metal (MIM) floating metallic membrane. Comparing the proposed high-capacitance-ratio MEMS switch with the ones in available literature, an acceptable insertion loss insulation, acceptable response time and high capacitance ratio (383.8) are achieved.