Abstract: The paper presents a resonant triggering circuit for driving high power reverse switched-on dynistor(RSD). The method for choosing the circuit parameters by optimization is proposed. Owing to the deformation and tail current of the current pulse found in preliminary experiments, two improvements are adopted in the circuit. First, a saturable magnetic ring is utilized to smooth the triggering current pulse. Secondly, a resistance-capacitor circuit is designed to absorb the redundant triggering energy. The experimental results show that the improved triggering circuit can offer an excellent triggering and conducting characteristic for RSD devices.