In this paper, five techniques to improve isolation of RF switch are reviewed which are material with fabrication process design, circuit design, resonant circuit, transmission line and resonator. Most of these isolation improvement techniques are applied in RF switch designs such as single pole single throw (SPST) and single pole multi throw (SPMT). Several solid-state devices are used for switching element such as PIN diode, MEMS, FET, HBT and HEMT. They are commonly used in satelite communication, radar system, instrumentation and base station applications. © 2006-2014 Asian Research Publishing Network (ARPN).