The design method, manufacture and testing results of new kind of T junction finline single pole double throw (SPDT) switch, which has only a controlling port with positive or negative pulses, was given. In order to increase the isolation and reduce the insert loss of the switch, some improving measures were taken in the circuit. The test results show that the insert loss≤1.5dB and the isolation≥30dB in Ka bands and the insert loss≤2dB and the isolation≥25dB in W bands.