By using impulse theorem, we have analyzed the mechanism of trigger thyristor by high-frequency pulse instead of width pulse .Through the establishment of an excitation circuit and a trigger thyristor circuit mathematical model and with the thyristor switch time, latching current, perceptual load and pulse transformer model parameters, we have calculated the thyristor conduction of minimum pulse width，cycle and pulse-width of equivalent high-frequency pulse column. Accordingly, we have designed thyristor "double narrow pulse triggering" program based on microcomputer control high-frequency pulse column. A prototype test waveforms and data of trigger microcomputer excitation system have shown that high-frequency pulse column and the excitation voltage waveform of three-phase controlled thyristor rectifier bridge rostrum are stable and have good symmetry. Also, the excitation voltage is stable and continuously adjustable. It has satisfied the requirements of wide pulse triggering.