The seismic test for the SDQH9 nuclear -grade electric actuator is introduced．The tests used an earthquake simulating shaking table and adopted the multi—frequency test. The tests were controlled with digital control using simulated time-histories，which was based on the required response spectrum. It detected the dynamic characteristics detect tests and carried out the tests of OBE（operational base earthquake）five times and the SSE（safety shutdown earthquake）one time. The inherent frequencies of prototype in X direction，Y direction and Z direction were respectively 72.59Hz、58.92Hz and 13.32Hz. In SSE test，acceleration magnitude on hand wheel was the biggest and the peak value of the three axial directions were respectively 20.22g、35g and 20g. These tests proved that the SDQH9 nuclear-grade electric actuator can work normally under the effect of earthquake load.