[en] According to the DPS-QKD (differential phase shift quantum key distribution) experiment demand for high-speed electro-optic modulator, the solid state switching technology and transformer isolation technology were applied to the design of a high speed electro optic modulator with a repetition rate of 45 kHz and a pulse of 2 kV. The modulation circuit includes two parts which can generate negative and positive 1000 V high voltage pulses respectively. The rise time and fall time of the positive high voltage pulse are 50.44 ns and 44.6 ns, and those of the negative high voltage pulses are 52.29 ns and 50.44 ns. The extinction ration is up to 23 dB when the modulator modulates the Pockels cell, which completely satisfies the need of DPS-QKD experiment. (authors)