Abstract: A broad-band plasma microstrip switch has been developed based on hollow cathode discharge. The basic principle of the plasma switch is replacing the metal element in RF MEMS by controllable plasma to perform the switch function in microstrip structure. A hollow cathode discharge under low pressure was employed to produce the plasma and the transmission characteristic of electromagnetic wave (EMW) was investigated experimentally. The results show that, when the plasma is presented, the switch is ON and the transmittance efficiency is 10%~30% for 1~9GHz EMW. When the discharge is extinguished, the switch is OFF. The response time of EMW signal to the voltage pulse is about 1μs. The present measures described in this article can achieve broad-band switch in microstrip line.