This invention provides a high-power semiconductor shutdown switch. A main switch selects a reverse switching dynistor RSD, and the RSD is a novel high-power semiconductor closed switch. Compared with a common thyristor, the RSD is strong in through-current capacity and small in current changing rate and time delay jittering. A fast-recovery thyristor is selected as a primary switch, therefore, energy loss in the current conversion process is reduced, and output efficiency is improved. The high-power semiconductor shutdown switch on the basis of switch current conversion of the RSD has the advantages of being capable improving the peak value current, the current changing rate and the output efficiency of an output pulse and reducing output time delay and jittering and particularly applicable to the field of application of the long-pulse large current.