Abstract: The structure of the semiconductor pulsed power switch reversely switched dynistor(RSD) was optimized by introducing a buffer layer. The numerical model of the device was established and the simulation analysis was carried out. The results show that the buffer layer can stop the electrical field and make the base region thinner. Compared with the conventional structure, the buffer layer structure improves the blocking voltage and reduces the turn-on voltage. According to the special operating mode of the RSD, the schemes for measuring key parameters such as the turn-on voltage and turn-off time for the RSD were proposed and realized by experiment. The high current turn-on experiments were carried out, in which the peak current of 173 kA passed through the RSD assembly of 7.6 cm diameter successfully. The main discharge voltage was 12 kV and the transferred electric charge amount was 32 C.